A 21-year-old man has been arrested over a series of arson attacks, police have said, after a fire at a house owned by Prime Minister Sir Keir Starmer.

The suspect was arrested in the early hours of Tuesday on suspicion of arson with intent to endanger life, according to the Metropolitan Police.

He remains in custody.

Emergency services were called to fires at the doors of two homes in north London within 24 hours of each other – one just after 1.35am on Monday in Kentish Town and the other on Sunday in Islington. Both properties are linked to Sir Keir.

Detectives were also checking a vehicle fire last Thursday on the same street as the Kentish Town property to see whether it is connected.

Part of the area was cordoned off as police and London Fire Brigade (LFB) investigators examined the scene.

Neighbours described hearing a loud bang and said police officers were looking for a projectile.

The prime minister is understood to still own the home, which was damaged by fire on Monday, but nobody was hurt. Pictures showed scorching at the entrance to the property.

Sir Keir used to live there before he and his family moved into 10 Downing Street after Labour won last year’s general election. It is believed the property is being rented out.

In the early hours of Sunday, firefighters dealt with a small fire at the front door of a house converted into flats in nearby Islington, which is also linked to the prime minister.

In a statement, police said: “As a precaution and due to the property having previous connections with a high-profile public figure, officers from the Met’s Counter Terrorism Command are leading the investigation into this fire.

“Enquiries are ongoing to establish what caused it. All three fires are being treated as suspicious at this time, and enquiries remain ongoing.”

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The prime minister’s official spokesman said: “I can only say that the prime minister thanks the emergency services for their work and it is subject to a live investigation. So I can’t comment any further.”

Kemi Badenoch has condemned the suspected arson attacks.

Writing on X, the Conservative leader said: “This is a shocking incident. My thoughts are with the prime minister and his family. No one should face these sorts of threats, let alone people in public service.

“It’s an attack on our democracy and must never be tolerated.”

Shadow justice secretary Robert Jenrick told Sky News on Tuesday: “It’s important that the prime minister and anyone in public life has their family, their homes, protected.

“It is absolutely wrong, disgraceful, for any individual to take the kind of action that we saw against the prime minister’s home.”

Robert Jenrick has claimed the UK is “already an island of strangers” after the prime minister faced criticism for using that phrase in a speech on migration.

The shadow justice secretary told Sky News Breakfast with Wilfred Frost that the UK was not at risk of becoming an “island of strangers”, as Sir Keir claimed, but that this already the reality.

Politics latest: PM under fire for ‘island of strangers’ phrase

Asked if he agreed with the PM’s language he said: “I think we already are. I think there are certain places in this country where people are not living side by side, where we are a very divided and segregated society.

“If you look at the centre of Bradford, for example, 50% of people were not born in the UK. If you look at the centre of Luton, almost 50% of people only arrived in the UK in the last 10 years. If you look at parts of Dagenham, the white British population has reduced by 50% in the last 25 years.”

In 2021, 80.1% of Bradford residents reported their country of birth as England according to the ONS, while in Luton the figure is 60.3% of the local population and in Barking and Dagenham it was 58.2%.

In Barking and Dagenham, about 85% of the population identified as white in 2001, which fell to 58.3% in 2011 and 44.9% in 2021.

In his speech on Monday announcing a package of measures to reduce net migration, Sir Keir pledged a new system that is “controlled, selective and fair”.

He said without the fair rules, “we risk becoming an island of strangers, not a nation that walks forward together”.

The comment has attracted criticism from within his own party, including Labour MP Sarah Owen, who said it could put the UK on “a very dark path”.

The chair of the Women and Equalities Select Committee said “fair and sensible” checks on immigration “should not equal blaming all the woes of our country on immigrants”.

“The best way to avoid becoming an ‘island of strangers’ is investing in communities to thrive – not pitting people against each other,” she added.

“I’ve said it before and will say it again, chasing the tail of the right risks taking our country down a very dark path.”

Nadia Whittome, the Labour MP for Nottingham East, also said the phrase mimicked the “scaremongering of the far-right”, while former shadow chancellor John McDonnell argued it was reminiscent of the late politician Enoch Powell.

Home Secretary Yvette Cooper defended the prime minister, pointing out “he also said we are a diverse nation and that he celebrates that”.

She added: “It is possible to both say that we have had huge benefits through generations by people coming, being part of communities, contributing, and also that that will continue to be important in the future, and also say we have a problem with the immigration system and that net migration needs to come down.”