LONDON — Boris Berezovsky, a self-exiled and outspoken Russian tycoon who had a bitter falling out with Russian President Vladimir Putin, has been found dead in southeast England. He was 67.
In recent years, the one-time Kremlin powerbroker-turned-thorn in Putin’s side fended off attacks on his character and on his fortune — sometimes successfully, sometimes not — in cases that often bore political undertones.
Thames Valley police said Saturday that Mr. Berezovsky’s death was being treated as unexplained.
They would not directly identify him, but when asked about him by name they read a statement saying they were investigating the death of a 67-year-old man at a property in Ascot, a town 25 miles west of London.
A mathematician-turned-Mercedes dealer, Mr. Berezovsky amassed his wealth during Russia’s chaotic privatization of state assets in the early 1990s. In return for backing former Russian President Boris Yeltsin, he gained political clout and opportunities to buy state assets at knockdown prices, making a fortune in oil and automobiles.
He also played a key role in the rise of Yeltsin’s successor, Putin, but later fell out of favor with the new leader and fled to Britain to seek political asylum in the early 2000s.
Mr. Berezovsky was one of several so-called Russian ‘‘oligarchs’’ to butt heads with Putin.
After coming into power, the Russian president effectively made a pact: the oligarchs could keep their money if they did not challenge him politically.
Those who refused found themselves in dire circumstances. Some were imprisoned — such as former Yukos Oil chief Mikhail Khodorkovsky — while others, like Mr. Berezovsky, fled.
Assets of these pariah businessmen, meanwhile, were acquired by state corporations or cooperative tycoons, often at bargain prices.
In the UK, Mr. Berezovsky allied himself with an array of prominent Kremlin critics. Among them was ex-KGB agent Alexander Litvinenko, who fled Russia with Mr. Berezovsky’s help after accusing officials there of plotting to assassinate political opponents.
Litvinenko died Nov. 26, 2006, after drinking tea laced with a lethal dose of the rare radioactive isotope polonium-210 in a London hotel. From his deathbed, Litvinenko accused the Kremlin of orchestrating his poisoning, and British police named former KGB agent Andrei Lugovoi as the prime suspect.
Both Lugovoi and the Kremlin denied the accusations, with the former instead claiming that Mr. Berezovsky — whom Russia consistently sought to extradite on a wide variety of criminal charges — engineered his friend’s death as a way of embarrassing the Kremlin and buttressing his refugee status.
Mr. Berezovsky, who considered Litvinenko a close friend, consistently denied the allegations.
In 2010, he won a libel case against Kremlin-owned broadcaster All-Russian State Television and Radio Broadcasting, which aired a show in which it was suggested he was behind the former agent’s poisoning.
Mr. Berezovsky recently has made headlines for costly legal battles, which have dealt serious blows to his finances.
Last year, the Russian business magnate was ordered to pay $53.3 million in legal costs to fellow Russian Roman Abramovich, the billionaire owner of Chelsea Football Club, after losing a multimillion-dollar legal battle against him.