They added there is no evidence to suggest the death is linked to the incident in Salisbury, where a former Russian spy Sergei Skripal and his daughter Yulia were poisoned with nerve agent which the United Kingdom government believes came from Russia.
Late Russian oligarch Boris Berezovsky, who died in London in 2013, was associated with Russian exile businessman Nikolai Glushkov, who was found dead late Monday in his London home.
Britain granted Berezovsky political asylum three years later on the grounds his life would be in danger if he went back home.
Nikolai Glushkov's death comes amid heightened concern following a nerve agent attack on a former Russian spy in England and as the government said it would investigate the deaths of a number of Russia-linked individuals which have raised suspicions. "The death is now being treated as unexplained", he said.
The road in London where Glushkov lived.
Glushkov worked in the 1990s for the state airline Aeroflot and Berezovsky's LogoVAZ auto company, according to media reports.
The 68-year-old Glushkov was a businessman in Russian Federation after the fall of Communism and had been a close associate of oligarch Boris Berezovsky, who was forced to flee Moscow after falling out with Vladimir Putin.
Counter-terrorism police were leading the investigation "because of associations that the man is believed to have had".
Berezovsky is one of 14 Russians whom USA intelligence services believe were assassinated in the United Kingdom, according to an investigation by BuzzFeed News.
His family feared he might have been murdered by enemies in Russian Federation, but British police and forensic experts concluded Berezovsky had committed suicide.
He alleged that Berezovsky and Alexander Litvinenko, a double agent who was killed with polonium poison, had both been on a Kremlin hitlist.
"I don't see anyone left on it apart from me". "Too many deaths [of Russian exiles] have been happening".
But there was "no evidence", it said, "to suggest a link to the incident in Salisbury", adding that the death is being treated as "unexplained".