Roman Abramovich says he paid fellow Russian billionaire Boris Berezovsky for “godfather” services

Roman Abramovich, the billionaire Russian oligarch and Chelsea Football Club, "betrayed and blackmailed" his political "godfather" Boris Berezovsky into selling his a valuable stake in the energy company Sibneft cheaply, Britain's High Court has heard.

Berezovsky, who lives in exile in London, is suing his former business partner Abramovich for more than $6 billion.

Abramovich's lawyer said that Berezovsky, 65, did help Abramovich, 44, in the acquisition of Sibneft, but that his contribution was entirely political and that Abramovich at all times controlled a majority of the shares, AFP reports.

Jonathan Sumption said "quite extraordinary conditions" prevailed in Russia following the collapse of communism in 1992, and it was impossible to get anywhere in business without political influence.

It was ''not easy'' for English lawyers to assess the behavior of people who lived in ''such a world,'' Sumption said, the Telegraph reports.

"There was no rule of law," said Mr Sumption. "The police were corrupt. The courts were unpredictable at best – at worst open to manipulation by major political or economic interest groups.

"Nobody could go into business without access to political power. If you didn't have political power yourself you needed access to a godfather who did."

Sumption said Berezovsky was a "highly controversial figure in Russian politics in the 1990s," and "a power broker."

He said Abramovich denied that Berezovsky ever had an interest in Sibneft, and that he was paid for his services as "godfather" to the younger businessman, Reuters reports. 

"Mr Berezovsky received between 1995 and 2002 at least $2 billion from businesses controlled by Roman Abramovich." 

By the late 1990s, Sumption said, Berezovsky effectively lived off this money.

"This was personal expenditure on a most exuberant scale: palaces in France, private yachts and aircraft, jewels for his girlfriend, valuable paintings."

The case is expected to last for more than two months.