Mumbai: Fugitive Russian billionaire Boris Berezovsky said he's helping to plan a revolution in Russia to overthrow President Vladimir Putin, the UK's Guardian newspaper reported quoting him.

Berezovsky, 61, said he was in contact with members of the Russian political elite who oppose Putin and is helping finance efforts to oust him.

``I am calling for revolution and revolution is always violent,'' Berezovsky was quoted as saying in a telephone interview.

Berezovsky, who rose to fame and accumulated wealth in the 1990s with help from the then President Boris Yeltsin, supported Putin's election in 2000. He later fell out with Putin and fled Russia for the UK in 2001 to avoid charges, including fraud. He escaped extradition in 2003 when the UK granted him political asylum.

The billionaire's comments provide further proof the UK authorities made a ``mistake'' in granting him asylum, Putin's spokesman Dmitry Peskov said in a telephone interview from Moscow.

``It is very hard for us to believe that London is granting asylum to a man who openly, being on British soil, speaking to British journalists, demands the use of force and violence in our country in order to change the existing political system,'' Peskov said.

The U.K. Foreign Office will review Berezovsky's statements.

``We deplore any call for the violent overthrow of a sovereign state,'' the Foreign Office said in a statement. ``We expect anyone living or working the UK to obey our laws, and we will look carefully at these and any future statements by Berezovsky in that light.''