Russian oligarch Boris Berezovsky has died, a friend has confirmed.

The exiled 67-year-old businessman, who last year lost a multibillion-pound High Court fight with Chelsea Football Club owner Roman Abramovich, was found dead at his home in Surrey.

Lord Tim Bell, the advertising and PR executive, said he could confirm his death.

A spokesman for his company, Bell Pottinger, said Berezovsky was found at his home in Ascot, Berkshire.

"His body was found by his bodyguard," he said. "No other details are available at this time."

It was widely reported the former mathematics professor had taken his own life, but that was not officially confirmed.

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.

Berezovsky emigrated to the UK in 2000 after falling out with President Vladimir Putin.

In fear of his life, he sought political asylum and moved to the South East of England, buying upmarket properties in Knightsbridge and Berkshire.