Prime Minister Sir Keir Starmer has spoken with Volodymyr Zelenskyy to give the Ukrainian president his backing after Donald Trump called him a “dictator”.

A Downing Street spokesperson said Sir Keir called Mr Zelenskyy this evening and shared his support for him “as Ukraine’s democratically elected leader”.

The prime minister “said that it was perfectly reasonable to suspend elections during war time as the UK did during World War II”, the statement continued.

He also “reiterated his support for the US-led efforts to get a lasting peace in Ukraine that deterred Russia from any future aggression”.

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In a post on X about the call, Mr Zelenskyy said: “The United Kingdom’s role in fortifying Europe’s defense and security is important for us.”

The “UK’s support matters indeed, and we will never forget the respect the British people have shown for Ukraine and our citizens”, he added.

The call was held after Mr Trump took aim at the Ukrainian president in a post on his Truth Social platform.

It is likely the war of words will come up again when Sir Keir meets Mr Trump in Washington next week, to discuss security and Ukraine.

Conservative leader Kemi Badenoch, who had been under pressure to condemn Mr Trump’s attacks, earlier said Mr Zelenskyy “is not a dictator. He is the democratically elected leader of Ukraine who bravely stood up to Putin’s illegal invasion”.

However, she said that Mr Trump “is right that Europe needs to pull its weight – and that includes the UK”.

She added: “We need to get serious. The PM will have my support to increase defence spending – there is a fully funded plan to get to 2.5% sitting on his desk.

“That should be the bare minimum. Starmer should get on with it, get on a plane to Washington and show some leadership. We cannot afford to get this wrong.”

Labour has pledged to raise defence spending to 2.5% of GDP, from about 2.3% now, but there is no timeline as to when. This week Ms Badenoch admitted the Tories tried to increase the funding to 3% while they were in office but there “wasn’t enough money to do so”.

It comes against the backdrop of a war of words between Mr Trump and Mr Zelenskyy, after officials from the US and Russia met in Saudi Arabia for talks to end the war – without representatives from Kyiv or Europe present.

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After Mr Zelenskyy complained of being excluded from the discussions, Mr Trump suggested the conflict could have been “settled very easily” and said “you [Ukraine] should have never started it”.

In response, Mr Zelenskyy said on Wednesday the American leader is living in a “disinformation space” created by Russia, which has repeatedly sought to blame Ukraine for the war.

Mr Trump has since hit back, saying Mr Zelenskyy “better move fast or he is not going to have a country left” and branding him a “dictator”.

Mr Zelenskyy was elected as president of Ukraine in May 2019. Elections were previously scheduled to go ahead in 2024, but they were not held as a result of martial law being in place.

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Ms Badenoch’s remarks come after reports that Tory MPs wanted her to take a stand on Ukraine since Mr Trump’s interventions.

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Europe is scrambling to respond to a US shift in foreign policy – with Mr Trump making clear that Washington no longer sees the defence of the continent as its primary concern.

Earlier on Wednesday, former prime minister Boris Johnson, who was in office when the war began, claimed Mr Trump’s statements are “not intended to be historically accurate but to shock Europeans into action”.

He asked when Europeans will “stop being scandalised about Donald Trump and start helping him to end this war?”

However on the other end of the political spectrum, Liberal Democrat leader Sir Ed Davey said that “calling Mr Zelenskyy a ‘dictator’ must be where the line is drawn”.

“It is my sincere hope that the whole political spectrum in the United Kingdom will speak with one voice in opposition to Trump’s lies.”

However defence secretary John Healey earlier reacted to the US president’s claim that Ukraine started the war.

The cabinet minister told reporters on a visit to Norway, near the border with Russia: “Three years ago, one country illegally invaded another, and since then, the Ukrainians have been fighting for their freedom.

“They’ve been fighting for their future, and they still are. So whilst all the focus may be on talks, not even negotiations, our concern as defence ministers is that we’re not jeopardising the peace by forgetting about the war.”