Berezovsky was part of Boris Yeltsin's inner circle in the latter years of his presidency, and became deputy secretary of Russia's security council.
He acquired his fortune in the 1990s after the privatisation of state assets following the collapse of Soviet Communism.
The businessman survived a number of assassination attempts, including a bomb in his car that decapitated his chauffeur.
More top news
Philippa has the latest weather update for the east
Philippa has the latest weather update for the west
Philippa has the weekend weather for the east