Police search home of Boris Berezovsky after unexplained death

Police have cordoned off the 67-year-old's home while police, including chemical, biological, radiological and nuclear (CBRN) trained officers, conduct a number of searches as a precaution, Thames Valley Police said. They later gave the all-clear.

Superintendent Stuart Greenfield said the death is being treated as unexplained.

He said: "We are aware the cordon is causing disruption to local residents and we apologise for any inconvenience, but it is important we take all necessary measures to ensure a full and thorough investigation can be carried out.

"I would like to reassure residents that we are confident there is no risk to the wider community.

"The property is part of a large estate so a number of roads are closed off at the moment and will remain so for the time being."

Lord Tim Bell, the advertising and PR executive, confirmed the death of the oligarch.

A spokesman for his company, Bell Pottinger, said Mr Berezovsky was found at his home in Ascot, Berkshire. "His body was found by his bodyguard," he said.

It was widely reported initially the former mathematics professor had taken his own life, but that was not officially confirmed.

Mr Berezovsky was part of Boris Yeltsin's inner circle in the latter years of his presidency, and became deputy secretary of Russia's security council.

He acquired his fortune in the 1990s after the privatisation of state assets following the collapse of Soviet Communism.

Mr Berezovsky emigrated to the UK in 2000 after falling out with President Vladimir Putin.

In fear of his life, he sought political asylum and moved to the South East of England, buying upmarket properties in Knightsbridge, London, and Berkshire.

The businessman survived a number of assassination attempts, including a bomb in his car that decapitated his chauffeur.

He became vocal and strong critic of Mr Putin's rule in Russia, where had become a wanted man.

In 2006 the Kremlin accused foreign-based opponents of poisoning to death former KGB spy-turned-dissident Alexander Litvinenko.

It was thought that Russia was in part referring to Mr Berezovsky, who denied the allegation and accused Mr Putin of personally being behind Mr Litvinenko's death from radioactive polonium-210 poisoning.

A South Central Ambulance Service spokeswoman said: "We were called at 3.18pm by a caller who was concerned about the welfare of a gentleman at an address in Ascot.

"We sent a number of ambulance officers and an ambulance to the address. The 67-year-old male was confirmed deceased at the scene."

A friend of Mr Berezovsky said that his family was "devastated", adding that she did not believe his death to be suspicious.

Sasha Nerozina told Sky News: "It is shocking, terrible news. It is not something you expect. He was full of life and love."

The businessman had been left "demoralised" by losing his high-profile legal battle with Mr Abramovich, as he had expected to win, she added.

However, Mr Berezovsky was "looking forward to adventures to come" and was so busy with work that he hardly slept, according to Ms Nerozina.

"Boris cannot be dead - it is almost incredible to put those words together," she said. "We expected him to outlive us all."

While he had feared for his life in the past, he had no such worries in his final months, said Ms Nerozina.

"There is nothing to be suspicious about, as far as I understand", she told Sky News.

Mr Berezovsky ran up more than tens of millions of pounds in legal bills in less than two years after the court battle with Mr Abramovich.

He also built up legal costs totalling more than £250,000 just two months after becoming embroiled in a case at the same court with his former partner, Elena Gorbunova, who sat at Mr Berezovsky's side throughout much of his battle with Mr Abramovich.

Earlier this week, the Daily Telegraph reported that the Russian oligarch would attempt to sell Red Lenin, an Andy Warhol screen print valued at between £30,000 and £50,000 by Christie's.

The artwork sold on Wednesday for £133,875 including the buyer's premium, according to the auction house's website.

Last year, Mrs Justice Gloster dismissed a series of claims by Mr Berezovsky - who wanted more than £3 billion damages - relating to deals done in Russia with Mr Abramovich.

In October, the judge was told by lawyers that Mr Berezovsky had agreed to pay £35 million towards Mr Abramovich's legal costs in the wake of her ruling.

She was given no detail of the amount of costs run up by Mr Berezovsky.

But legal magazine The Lawyer said the case was thought to have generated "total fees" of more than £100 million.

Mr Berezovsky had sued and accused Mr Abramovich of blackmail, breach of trust and breach of contract.

He said the billionaire Russian businessman had "intimidated" him into selling shares in a Russian oil company at a fraction of their value and broken a promise made during a deal relating to a Russian aluminium company.

Mr Abramovich said the claims had "no merit".

Mrs Justice Gloster ruled in Mr Abramovich's favour in August following a trial - staged in London between October 2011 and January - at which both men gave evidence.

The judge described Mr Berezovsky as an "unimpressive, and inherently unreliable, witness" but said she found Mr Abramovich to be a "truthful, and on the whole reliable, witness".

Last month, the High Court heard that Mr Berezovsky had run up over £250,000 in costs in his legal battle with Ms Gorbunova, which started in December.

Mr Justice Mann was given detail of the scale of lawyers' fees during a preliminary hearing and described the costs of the case as "lavish".

The judge said Ms Gorbunova, who had two children with Mr Berezovsky, was complaining that she had not been given millions promised by him.

He said it was anticipated that Mr Berezovsky would "vigorously contest" Ms Gorbunova's claims.

Mr Justice Mann said she had been Mr Berezovsky's "long-time partner" until last year.