The Federal Security Service has charged Boris Berezovsky with plotting the violent overthrow of President Vladimir Putin's government, the self-exiled businessman's lawyer said Monday.

The charges represent an escalation in the legal proceedings against strident Putin critic Berezovsky, whose trial in absentia on fraud charges opened Monday.

They may also further aggravate tensions between Russia and Britain, which has filed for the extradition of former KGB agent Andrei Lugovoi to face charges of murder in the poisoning death of Alexander Litvinenko, also a former security forces agent.

Russian officials have repeatedly said the request for extradition would not be granted.

Berezovsky's lawyer, Andrei Borovkov, said the new charges, which carry a sentence of 12 to 20 years, had been filed in June and stemmed from a number of statements his client had made to the press in interviews over the past year.

"The charge is very broad," Borovkov said by telephone. "It includes all of the incidents, including that with the Guardian."

In an interview published in the newspaper in April, Berezovsky said, "We need force to change this regime." He added, "There can be no change without force, pressure."

Berezovsky, who lives in Britain with political refugee status, backed away from the comments in a statement released later on the same day the interview was published.

"I do support direct actions," the statement read. "I do not advocate or support violence."

Comments in interviews with Ekho Moskvy radio and Agence France Press at the start of last year were also cited in the charges, his lawyer said.

An FSB spokesman contacted Monday would neither confirm nor deny that the charges had been filed.

Berezovsky described the charges on Monday as "nothing new," The Associated Press reported.

Alex Goldfarb, who co-authored a book about Litvinenko with his widow, and who is an associate of Berezovsky's, said that the charges were a smokescreen.

He said that they were "all part of a public relations offensive meant to repair the damage done by the Litvinenko case," The Associated Press said.

The news of the FSB charges against Berezovsky surfaced on the same day the billionaire's lawyers reiterated that they would not represent him in the fraud case.

Berezovsky is charged with embezzling 214 million rubles ($8.3 million) from state-owned airline Aeroflot, as well as for money laundering in the transfer of 16 million rubles of those funds from 1996 to 1999.

The charges carry a maximum sentence of 10 years in prison.

Berezovsky has labeled the case against him a farce and instructed his lawyers not to take part in the proceedings, so his lawyers made an appearance Monday to explain why it would be their last.

"We confirmed ... that Berezovsky and his lawyers will not participate in this trial," Borovkov said.

Judge Igor Sheremetyev instructed the Moscow bar association to appoint a state-funded lawyer to represent Berezovsky, and adjourned the case until July 12.

Berezovsky, who claims to have helped finance Putin's rise to power, fled the country in 2001, a year after Putin's election. He was granted asylum by Britain in 2003, after a court expressed doubts about his chances of receiving a fair trial in Russia.