Counter-terrorism police are investigating the death of a man in south-west London amid reports that a Russian businessman who was a close friend of Putin critic Boris Berezovsky has been found dead.
Scotland Yard said a man in his 60s was found at a home in Clarence Avenue, New Malden, on Monday and that the cause of his death is unexplained.
The force said in a statement: "At this stage the Met Police Counter Terrorism Command is leading the investigation as a precaution because of associations that the man is believed to have had.
"There is no evidence to suggest a link to the incident in Salisbury."
Russian media reported that Nikolai Glushkov, 69, the former deputy director of airline Aeroflot, had died.
The businessman was outspoken after the death of his friend Berezovsky, telling the Guardian in 2013 he would "never believe" he took his own life.
Mr Berezovsky, a friend of murdered spy Alexander Litvinenko and thorn in the side of Russian President Vladimir Putin, was found hanged in the bathroom of his Berkshire home in 2013. An inquest recorded an open verdict.
Police and MI5 are to look into allegations that a string of deaths on UK soil may be linked to Russia, including the Berezovsky case.