His statement had an immediate impact on Russia's relations with the UK, already strained by accusations from London-based dissidents including Berezovsky that the Kremlin was behind the poisoning death of Alexander Litvinenko, an ex-Russian spy.


Dmitry Peskov, the Kremlin's deputy spokesman, said on Russian satellite television: "The main thing it seems to me is that he has put the British authorities and the British justice system in an awkward position.


"We have heard open calls for the forceful overthrow of power in another state ... from the lips of a person who was given political asylum in a court ruling.


Logic dictates that such statements should lead to a review of that decision."


Jonah Hull, Al Jazeera's correspondent in Moscow, said that Berezovsky's accusations are nothing new, but this time the Kremlin is rattled.


"Berezovsky has made very good use of his years in exile in Britain launching sweeping attacks on the Kremlin and on President Putin himself."


"In the past he has alluded to contacts his has with opposition politicians saying that he is financing them and advising them toward a change of leadership by democratic means.


"The difference here is though is this very pointed language referring to overthrow "by force" and that he is now talking about contacts with senior Russian politicians, members of the Russian elite inside the Kremlin, quite possibly members of rival factions vying now for power with elections looming.


"That in particular will have the Kremlin rattled."


Berezovsky said he was offering his "experience and ideology" to his contacts in Russia's political elite, adding: "There are also practical steps which I am doing now, and mostly it is financial."


Extradition appeal


Russia has for years been trying to extradite Berezovsky from his base in London to face corruption charges at home. But plans have been foiled because of Berezovsky's refugee status.


"Berezovsky has made very good use of his years in exile in Britain launching sweeping attacks on the Kremlin and on President Putin himself"

Jonah Hull, Al Jazeera

Sergei Lavrov, Russian foreign minister, told a news conference: "It is a question for the British authorities. They know perfectly well what this person is up to."


Yuri Chaika, Russian prosecutor-general, said he had ordered a criminal investigation over Berezovsky's remarks, though the tycoon is outside Russia's jurisdiction.


"I've already given an instruction to the relevant authorities to open a criminal case," Chaika said in televised remarks.


Berezovsky was at the centre of allegations which were angrily denied by the Kremlin, that Putin played a part in Litvinenko's death in London last November.


Berezovksy was a pall-bearer at Litvinenko's funeral and his comments are likely to raise the political temperature inside Russia in the run-up to parliamentary elections in December and a presidential vote in 2008.


A mathematician who made a fortune from business deals in the economic free-for-all that followed the collapse of Soviet rule, Berezovsky played a part in bringing Putin to power in 2000.


But he later fell out with Putin and fled to Britain when a criminal investigation was opened into his business dealings.