Russian oligarch and Kremlin critic Boris Berezovsky was found dead on Saturday in his home in Surrey, England, Russian state media reported.

London police have opened an investigation into his death. At this point, the cause of death is not known.

Russia's Channel One reported that his body was found in the bathroom of his home, and that he had suffered a heart attack last week.

The exiled Russian died at the age 67, according to a Facebook post from his son-in-law Egor Schuppe, broadcaster Russia Today reported. Schuppe said Berezovsky was depressed and failed to keep in touch with friends and acquaintances.

Berezovsky's lawyer Aleksandr Dobrovinksy said the oligarch had committed suicide. "I got a call from London telling me that he had committed suicide," he told television channel Russia 24.

"He was a difficult man. A move of disparity? Impossible to live poor? A strike of blows? I am afraid no one will get to know now," Dobrovinksy said on his social network page.

In December, Berezovsky was ordered to pay 35 million pounds (56 million dollars) in legal costs after losing his claim for damages against rival Roman Abramovich, the High Court in London said.

Berezovsky lost his legal bid to claim more than 3 billion pounds in damages from Abramovich in August. The case centered on the two men's business relations in Russia after the fall of communism in the early 1990s.

Abramovich, the multi-millionaire owner of Chelsea Football Club, won the case at the High Court in August, which was described at the time as among the "world's most expensive private legal action." 

Berezovsky was born in Moscow in 1946 to a Jewish father and a mother with Jewish roots. He accumulated his wealth in the years following the collapse of Soviet Russia, when he acquired local firms, among them oil companies and television stations, rising to prominence during the term of Boris Yeltsin in the nineties.

Valued in recent years at some $900 million, Berezovsky was worth about three times that in the nineties.

Russian media reported recently that Berezovsky, once the richest man in Russia, suffered heavy losses. The reports say Berezovsky began selling his personal assets, including a famous Andy Warhol print called Red Lenin, which was auctioned last week for $200 thousand. Berezovsky went on to sell some of his classic car fleet, including a 1927 Rolls Royce.

Before going into business, Berezovsky was a mathematics professor and a member of the Russian Academy of Sciences, as well as a member of the lower house in Russian parliament, the Duma.