Berezovsky, who faces a number of charges in Russia, was a key Kremlin insider in the 1990s, but left Russia after coming into conflict with Putin and was granted political asylum in Britain in 2003.

Berezovsky said Putin had violated the constitution and therefore his ouster was legitimate -- and forecast a possible uprising like Ukraine's Orange Revolution between elections in December and March.

"I don't fund parties which are openly presented on the Russian political scene because it's absolutely useless, but I (fund) people who are underground and that are trying to fight against the regime," he told reporters.

"They are doing what underground movements all around the world are doing, they prepare people to go to the streets, to fight, to use force power against a criminal government."