A third person has been charged over arson attacks on two properties and a car linked to Prime Minister Sir Keir Starmer.
Petro Pochynok, 34, of north London, has been charged with conspiracy to commit arson with intent to endanger life, the Metropolitan Police said.
He was arrested in Chelsea, west London, on Monday and will appear at Westminster Magistrates Court on Wednesday morning.
He is the second Ukrainian national to be linked to the incidents after Roman Lavrynovych, 21, of Romford, was charged with three counts of arson with intent to endanger life.
A Romanian national, Stanislav Carpiuc, 26, of Romford, has also been charged with conspiracy to commit arson with intent to endanger life, police have said. They appeared before magistrates on 16 and 20 May respectively, were remanded in custody, and are due to appear at the Old Bailey on 6 June.
Pochynok is accused of conspiring with the other two defendants "and others unknown" to damage a property using fire, intending to do so, as well as intending to or being reckless with regards to whether lives were endangered, the Met's Counter Terrorism demand added.
The charges are related to three fires - between 8 and 12 May in north London.
The first took place in the early hours of 12 May at a house in Kentish Town where the prime minister lived with his family before the election. Damage was caused to the property's entrance, but nobody was hurt.
The second blaze, involving a car on the same street, took place on 8 May.
A third fire broke out at the front door of a house converted into flats in Islington, which is also linked to Sir Keir, on 11 May. One person was taken to safety via an internal staircase by crews wearing breathing apparatus.
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