The wife of a Russian banker shot in London last week appealed on Thursday for anyone with information to come forward, describing the attack as an "act of pure unexpected violence".

German Gorbuntsov, 45, remains in a critical but stable condition in hospital after he was shot several times with a pistol on March 20 as he entered his apartment block near the Canary Wharf financial district.

Police have yet to make any arrests but they are seeking a man who was seen running away from the scene, as well as the taxi driver who dropped Gorbuntsov off near the building shortly before the shooting.

"This is a very emotional and complicated time for us," said the victim's wife, Lorissa, in a statement issued through London's Metropolitan police.

"We as a family would like to appeal for any person, in this country or outside the UK, to come forward and provide the police with any information which will assist in the capture of the person or persons behind the attempted murder of my husband German.

"This is an act of pure unexpected violence... Please come forward so that justice can prevail."

There has been speculation in the Russian media that the attack was linked to an assassination attempt on Gorbuntsov's business partner and co-owner of the Konvers Group, Alexander Antonov, in 2009.

It has also been reported that Gorbuntsov was the target of several investigations by Moldovan prosecutors after a bank he owned, Universalbank, closed down in February.

Detectives have said they are keeping an open mind about the motive.