Police were called by ambulance services at 10.46 p.m. local time to an address in New Malden, in the borough of Kingston.
Police and MI5 are expected to examine allegations that a series of deaths on United Kingdom soil, including the Berezovsky case, may be linked to Russian Federation.
He noted that a large number of Russian exiles including Berezovsky, and Berezovsky's close friend Alexander Litvinenko, had died under mysterious circumstances.
Who was Nikolai Glushkov, and how did he die?
Glushkov, who was 68 when he died on Tuesday, rose to wealth in the 1990s as a lieutenant of Berezovsky, the oligarch who amassed huge wealth and influence under the Boris Yeltsin's government but fled to Britain after falling out with Vladimir Putin.
A Met spokesperson said they believe they know the identity of the man, and his next of kin have been informed, but formal identification is yet to take place. According to investigators, Boris Berezovsky an oligarch and associate of Glushkov created his "lobby" at Aeroflot's leadership, embedding people from the firms he controlled there.
Glushkov was formerly an employee of Berezovsky, one of the billionaires who bankrolled the 1996 re-election of President Boris Yeltsin. He, however, lost Putin's favor and fled to London, where he often criticized the Russian government.
Mr Glushkov was arrested in 1999 and put on trial for allegedly embezzling $7m from Aeroflot, and sentenced in 2004 to three years, three months in prison.
Russian media have contacted those individuals closest to Glushkov to find out the reason behind his death. But Russian courts continued to pursue him.