Moscow ? Boris Berezovsky, the exiled Russian tycoon who has emerged as one of the Kremlin’s most vocal opponents, called Friday for the use of force to oust President Vladimir Putin and claimed he has support from some in the country’s political elite.

In response, Russia’s chief prosecutor opened a criminal case against Berezovsky on charges of plotting a coup, saying in a statement that the remarks “contained an open call to overthrow the constitutional order of Russia.” It also said it would ask British authorities to strips Berezovsky of asylum and to extradite him to Russia.

London’s Metropolitan police began an investigation Friday into whether Berezovsky’s comments, first published in Friday’s Guardian newspaper, violated any British laws.

A former Kremlin insider, Berezovsky fell out with Putin and fled to Britain, which granted him refugee status in 2003.