"Officers found nothing of concern in the property and we are now progressing the investigation as normal," a statement from police said earlier, adding that the majority of the cordon put in place around the property has now been lifted. Berezovsky -- who had survived a number of assassination attempts -- amassed a fortune through oil and automobiles during Russia's chaotic privatization of state assets following the collapse of the Soviet Union in the early 1990s. Once a member of Russian President Boris Yeltsin's inner circle, Berezovsky fell out with Yeltsin's successor, Putin, and fled Britain in the early 2000s to escape fraud charges that he said were politically motivated. He became a strident and frequent critic of Putin, accusing the leader of ushering in a dictatorship, and accused the security services of organizing 1999 apartment house bombings in Moscow and two other Russian cities that became a pretext for Russian troops to sweep into Chechnya for the second war there in half a decade. Putin's spokesman acknowledged Sunday that the Russian president considered Berezovsky an enemy. "We know for certain that he spared no expense in support of processes, within Russia and beyond, that could be said to have been directed against Russia and Putin," spokesman Dmitry Peskov said on the independent cable television channel Rain. "He definitely was Putin's opponent, and unfortunately not only his political opponent, but most likely in other dimensions as well." In recent years, Berezovsky fended off legal attacks that often bore political undertones -- and others that bit into his fortune. Russia repeatedly sought to extradite Berezovksy on a wide variety of criminal charges, and the tycoon vehemently rejected allegations over the years that he was linked to several deaths, including that of slain journalist Anna Politkovskaya and ex-KGB agent Alexander Litvinenko. Berezovsky won a libel case in 2010 against a Kremlin-owned broadcaster that aired a show in which it was suggested he was behind the poisoning of Litvinenko, who had fled Russia with Berezovsky's help after accusing officials there of plotting to assassinate political opponents.