Boris Berezovsky, an exiled Russian tycoon, has been found dead at his home in Surrey, UK.
The circumstances of the death of Boris Berezovsky – a wanted man in Russia, and an opponent of President Vladimir Putin – at the age of 67, are not yet known.
Thames Valley Police said the death, at a property in Ascot, Berkshire, was being treated as unexplained.
The area around the property has been cordoned off to allow the investigation to take place, the force said.
The inquiry was at a very early stage and more details will be released when available, it added.
A South Central Ambulance Service spokeswoman said it had been called to the property at 15:18 GMT.
“We sent a number of ambulance officers and an ambulance to the address. The 67-year-old male was confirmed deceased at the scene,” she said.
A former Kremlin power-broker whose fortunes declined under Vladimir Putin, Boris Berezovsky emigrated to the UK in 2000.
Last year, he lost a £3 billion ($4.7 billion) damages claim against Chelsea Football Club owner Roman Abramovich.
Boris Berezovsky claimed he had been intimidated by Roman Abramovich into selling shares in Russian oil giant Sibneft for a “fraction of their true worth”.
The allegations were completely rejected by the London Commercial Court judge, who called Boris Berozovsky an “inherently unreliable” witness.