A Metropolitan Police spokesman issued this statement: “A man was shot a number of times as he entered a block of flats by a suspect who is described as white, six feet tall and of slim build. He was wearing dark clothing and seen running away. Officers and the London Ambulance Service attended and a man, aged in his forties, was taken to hospital. His condition is described as critical but stable. Detectives from the Trident Gang Crime Command are investigating and are treating the shooting as attempted murder.”

German Gorbuntsov, who formerly owned banks in Russia and Moldova, lived as an exile in Britain, is in a critical condition in hospital after being shot at a block of flats in Byng Street. He is reported to have said he would be killed if he returned to Russia.

He is on Moldova’s wanted list over allegations of an illegal bank takeover and embezzlement.

According to Russian media, Gorbuntsov was named as a suspect and a witness in an attack on the financier Alexander Antonov in Moscow in 2009.

Russia's Kommersant newspaper suggested on Friday a possible link between the London shooting and the investigation in Moscow into the attempted killing of Antonov.

Russian police have never established who ordered the attack on Antonov, although three Chechen men were convicted of attempted murder and given long jail sentences in 2010. Detectives in Moscow are understood to have reopened the investigation into the shooting of Antonov earlier this year after Gorbuntsov provided new testimony.

Vadim Vedenin, Gorbuntsov's lawyer in Moscow, told Kommersant that the testimony supplied to police by his client had implicated two of his former business partners in the Antonov attack. Both businessmen deny any involvement in the attack.