British spies are investigating whether Russia was behind a series of arson attacks on Keir Starmer’s property, The Mail on Sunday can reveal.

Police say that two Ukrainians and a Romanian who have been charged over the incidents, involving two houses and a car linked to the Prime Minister, had conspired with ‘others unknown’.

Now senior official sources have disclosed that MI5 is examining potential links between the three men and Vladimir Putin’s regime.

Although no one was injured in the fires, any suggestion that the attacks on a British Prime Minister had been ordered by the Kremlin would represent an extraordinary escalation in tensions between the two countries.

The three men, Petro Pochynok, 34, Stanislav Carpiuc, 26, and Roman Lavrynovych, 21, have been charged with conspiring to damage a house currently rented out by Sir Keir in Kentish Town, north London, another in nearby Islington where he previously lived, and a car he sold to a neighbour last year.