Mr Matheson described the proposed suspension as “excessive and unfair”.
The Parliamentary Commissioner for Standards upheld two allegations of sexual misconduct against Mr Matheson made by a former member of staff.
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He allegedly invited her on a private trip abroad and “the invitation was sexually motivated, unwanted, and had placed the complainant under pressure and intimidated her”, according to the report.
During a work event outside Parliament, he also “linked arms with her; made personal comments about her appearance while looking at her suggestively; made her hold his hand as they left and insisted on accompanying her to her bus stop; and once there invited her back to his flat, kissed her twice on the forehead and attempted to kiss her on the mouth”.
The report states that the commissioner “concluded that these were all unwanted and unwelcome sexual advances”.
A Labour spokesperson said: “This is an incredibly serious case. There must be a zero tolerance for sexual harassment and the Labour Party has acted immediately following the ICGS findings.
“We will now select a candidate that the people of Chester can be proud to vote for.”
Mr Matheson has been the MP for the City of Chester since 2015.
“I have today, with great sadness, tendered my resignation as Member of Parliament for the City of Chester,” he said in a statement.
“This follows publication of a report which had found me guilty of sexual misconduct.
“From the start I accepted I had committed a minor breach of the code and had hoped that an honest and open approach would stand me in a fair light.
“This has proven not to be the case and I am dismayed that I have been found guilty of several allegations that I know to be untrue.
“Indeed my insistence on what I know to be true – that I had no sexual motivation in this matter – was held against me as a refusal to accept my guilt, and caused an increased sanction which I felt was disproportionate.
“Despite provable factual inaccuracies in the sanctions report, my appeal against sanction was not even considered, for the same reason.
“Therefore, I faced a suspension from the House of four weeks.
“Whilst I believe that this is an excessive and unfair penalty, I cannot challenge the process further. I believe that the honourable and right thing to do now is to resign my seat and seek to rebuild my life elsewhere.
“I would ask for privacy for my family. This matter has also caused a great toll on my health, requiring my hospitalisation, and I ask that my privacy is respected while I recover.
“I will forever be grateful to my constituency, and my party, for giving me the honour to serve, and I apologise to the people of Chester, and to the House of Commons, for the disrepute I have brought.
“I once again apologise to the complainant in my case, for the hurt I have caused.”
His resignation means there will now be a by-election in the City of Chester.
Mr Matheson retained the seat with a 6,164 majority in 2019.
Responding to the report, Mike Clancy, general secretary of Prospect union, said: “It is worrying however that while he was being investigated he remained able to attend the Houses of Parliament.
“In no other workplace would someone being investigated for such serious offences be free to continue visiting it. MPs must get a grip on this issue – it is simply unacceptable that those working in Parliament continue to be put at risk in this way.”
Israeli defence minister Yoav Gallant has held talks over the possibility of expanding Israel’s military offensive – as tanks were pictured on the country’s border with Lebanon.
In a statement on Saturday, Mr Gallant’s office said he was conducting “an operational situation assessment” regarding what it called “the expansion of IDF (Israel Defence Forces) activities in the northern arena”.
Israeli tanks and troops were later pictured near the border, in what Sky News’ security and defence editorDeborah Haynes said is the “clearest sign yet” that Israel’s conflict with Hezbollah is “about to expand even further”.
The military said it was mobilising three more battalions of reserve soldiers to serve across the country. It had already sent two brigades to northern Israel to prepare for a possible ground invasion.
The deployment comes after Hezbollah confirmed that its leader of more than three decades Hassan Nasrallah was killed in an Israeli airstrike in Beirut on Friday.
The militant group – which is aligned with Iran – vowed to continue its fight against Israel even as attacks continued to bombard areas around Lebanon’s capital.
At least six people were killed in the strikes – not including Nasrallah – and 91 were wounded, according to preliminary figures from Lebanon’s health ministry.
The United Nations high commissioner for refugees said that airstrikes led to the displacement of “well over 200,000” people inside Lebanon.
“More than 50,000 Lebanese people, and Syrians living in Lebanon, have crossed the border into Syria,” Filippo Grande wrote on X on Saturday.
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‘Israel is on the move’
In his first public remarks since the killing, Israeli Prime Minister Benjamin Netanyahu described Nasrallah as a “terrorist” and said his killing would help bring displaced Israelis back to their homes in the north and would pressure Hamas to free Israeli hostages held in Gaza.
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Netanyahu: Nasrallah ‘was the terrorist’
But with the threat of retaliation high, he said the coming days would bring “significant challenges” and warned Iran against trying to strike.
“There is no place in Iran or the Middle East that the long arm of Israel will not reach, and today you already know how true this is,” Mr Netanyahu said.
“We have great achievements, but the work is not yet complete. In the coming days we will face significant challenges, and we will face them together,” he added.
“We are determined to continue to strike at our enemies, return our residents to their homes, and return all our abductees. We do not forget them for a moment.
“Israel is on the move.”
Iranian Supreme Leader Ayatollah Ali Khamenei condemned the killing and announced five days of mourning. He said Lebanon will make Israel “regret their actions” and Nasrallah’s blood “will not go unavenged”.
In a letter to the UN Security Council, Iran’s UN ambassador Amir Saeid Iravani asked for an “emergency meeting” of the 15-member body, calling on it to “compel Israel” to cease all military action in both Gaza and Lebanon and “comply with relevant UNSC resolutions”.
Meanwhile, hundreds of protesters took to the streets of Tehran, waving Hezbollah flags and chanting “death to Israel” and “death to Netanyahu the murderer”.
People also gathered in the Lebanese city of Sidon and in Amman, Jordan, to mourn Nasrallah. The 64-year-old had countless followers across the Arab and Islamic world, but was viewed as an extremist in much of the West.
Most of all, is the Middle East about to erupt into a regional conflict that threatens us all? That’s been the warning for almost a year, so is it about to happen?
Hezbollah is a designated terrorist organisation for the US, UK and other Western nations. It has killed hundreds of their citizens over the years.
There is no doubt President Joe Biden has felt what he called a “measure of justice” that Nasrallah has been killed.
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But there is also a fear of what comes next. From the president down we are hearing urgent calls for de-escalation and a diplomatic solution.And the US has rushed military assets to ward off Hezbollah’s patrons in Iran doing their worst. But will that be enough?
US-led diplomacy to contain the Middle East crisis has failed.
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A senior Middle Eastern diplomat told Sky News the assassination is a kick in the teeth for the US president.
“For all the bombs and billions he has given the Israelis,” he said, “the least they could have done for him in the last weeks of his presidency was a ceasefire in the region”.
With diplomacy stalled, what happens next depends on both Iran and Israel.
For its part, Iran may feel it has no alternative but to weigh in. It may fear the massive missile arsenal it supplied is so jeopardised it must intervene and save Hezbollah.
Iranians have long regarded Hezbollah as an insurance policy for the day Israel might attack Iran itself. If it sees its ally close to total collapse, might it then weigh in?
If it does, Israel’s allies led by America might feel compelled to come to its defence. The full scale war feared for almost a year could engulf the region.
But there are good reasons for Iran not to rush to action.
The Middle East seems a dangerous and unpredictable place but certain rules and assumptions apply, even in all its chaos.
For all their fanaticism, the ayatollahs of Tehran are pragmatic and seek the preservation of their grip on power above all. That has been a rule of the Middle Eastern jungle since they seized power 45 years ago.
Is it pragmatic or wise to up the ante and more directly support Hezbollah, when it is at its weakest? The Iranian regime is not that strong either, crippled economically by sanctions and mismanagement, and socially and politically by months of civil unrest, albeit now quashed.
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There are limits too to what Iran could achieve with direct military intervention anyway in a war that is 2,000km from its borders. The Iranians may conclude this round in the war against Israel is over. They think in long time spans, after all. Time to regroup and move on to fight another day?
There will no doubt be days more of sound and fury, like we have seldom seen before. The mourning and funerals of Nasrallah and his lieutenants are likely to be the focus of intense anger and will raise tensions. But what happens afterwards?
That also comes down to Israel.
It may now feel it has the wind in its sails and seize the moment to invade Lebanon on the ground to push Hezbollah back from the border. That would be an extremely dangerous moment too, potentially drawing in supportive militia and Iranian forces based in Syria.
The hills of southern Lebanon are a treacherous country for a military like Israel’s that relies on infantry and tanks. They could be drawn into a lengthy and punishing campaign that could then destabilise the region.
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Then there is Lebanon itself. An uneasy compromise between the warring factions of its civil war in the 1970s and 80s has held for decades but its always fragile status quo is now threatened. The chessboard of its multi-denominational politics has potentially been upended by the removal of its most powerful player.
If Lebanon descends back into factional fighting, regional stability will be undermined too.
The Middle East is in grave danger of further escalation. Western and regional diplomats are working round the clock to pull it back from the brink but recent efforts have all ended in failure and neither Israel nor Hezbollah seem to be listening.
The Israel Defence Forces (IDF) said it carried out a “precise strike” on Hezbollah’s “central headquarters”, which it claimed was “embedded under residential buildings in the heart of the Dahieh in Beirut”.
The first wave of attacks shook windows across the city and sent thick clouds of smoke billowing into the air.
While Israel stressed it had been a “precise” strike, preliminary figures from Lebanon’s health ministry confirmed at least six other people were killed and 91 were wounded.
Israel said Nasrallah was the intended target and initially there were claims he had survived.
However, after several hours of confusion, his death was confirmed by Israel.
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“Hassan Nasrallah will no longer be able to terrorise the world,” the IDF said.
Hours later, a defiant Hezbollah confirmed Nasrallah’s death but vowed their fight with Israel would continue after confirming they had fired upon sites in northern Israel.
“The leadership of Hezbollah pledges to the highest, holiest, and most precious martyr in our path full of sacrifices and martyrs to continue its jihad in confronting the enemy, supporting Gaza and Palestine, and defending Lebanon and its steadfast and honourable people,” they said.
Alongside claiming to have killed Nasrallah, the IDF said it had killed a number of other commanders, including Ali Karaki, the commander of the southern front.
The country’s military said the strike was carried out while Hezbollah leadership met at their underground headquarters in Dahieh.
In the aftermath of the most recent attacks, an Israeli military spokesperson declined to comment on whether US-made Mark 84 heavy bombs were used in the strike against Nasrallah.
“The strike was conducted while Hezbollah’s senior chain of command were operating from the headquarters and advancing terrorist activities against the citizens of the State of Israel,” Lieutenant Colonel Nadav Shoshani said in a media briefing.
He continued: “We hope this will change Hezbollah’s actions.”
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6:17
Hezbollah leader killed says IDF
He added the number of civilian casualties was unclear but blamed Hezbollah for positioning itself in residential areas.
“We’ve seen Hezbollah carry out attacks against us for a year. It’s safe to assume that they are going to continue carrying out their attacks against us or try to,” he said.
Meanwhile, Iran said it was in constant contact with Hezbollah and other allies to determine its “next step”, but Reuters reported the country’s supreme leader was transferred to a secure location in light of the latest attack.
Speaking after the attack, Ayatollah Ali Khamenei called on Muslims “to stand by the people of Lebanon and the proud Hezbollah” and said: “The fate of this region will be determined by the forces of resistance, with Hezbollah at the forefront,” state media reported.
Nasrallah’s death will be a blow to Hezbollah as it continues to reel from a campaign of escalating Israeli attacks.
Nasrallah is latest Hezbollah leader to fall
While Nasrallah’s death is certainly the most high-profile of recent attacks, it continues a trend of Israel targeting Hezbollah’s leadership structure.
Also on Saturday, in the early hours of the morning, the commander of the group’s missile unit and his deputy were killed in another Israeli attack in southern Lebanon.
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