Nikolai Glushkov was found dead Monday night.
Nikolai Glushkov, 68, was discovered dead late on Monday at an address in Clarence Avenue in suburban south-west London.
Glushkov had lived in London in recent years, after being granted political asylum in Britain.
A lawyer says a Russian businessman who associated with a prominent critic of the Kremlin has died in London.
The Metropolitan Police said an investigation is underway, but did not name Mr Glushkov.
"The death is now being treated as an unexplained".
Berezovsky was found dead at home in 2013, an incident which had some hallmarks of suicide, but which Gluskhov was adamant was politically motivated.
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Counter-terrorism police were leading the investigation "because of associations that the man is believed to have had".
The news was confirmed Tuesday on Facebook by Moscow Times board member Damian Kudryavtsev, who was close to both Glushkov and Berezovsky.
In the 1990s, Glushkov worked for the state airline, Aeroflot, along with Berezovsky's LogoVaz auto company.
Berezovsky is one of 14 Russians whom USA intelligence services believe were assassinated in the United Kingdom, according to an investigation by BuzzFeed News.
"I don't think I've seen him in the last week or so, I hadn't noticed him, but I don't know what's happened - the police said they are still searching and there are lots of police cars".
According to the RBK Russian news site, Glushkov was found guilty of abuse of power in a financial scandal at Aeroflot, and was convicted in absentia of fraud previous year for allegedly stealing more than $100 million from the company.
United Kingdom counter-terror police are investigating the "unexplained death" of a Russian businessman in London.