Britain is set to open a judicial inquiry into the death of a Russian tycoon to establish how he died in the locked bathroom of his vast mansion near London.

Boris Berezovsky, who survived years of power struggles and assassination attempts in Russia, was found dead last week in his home in Ascot, a town close to Queen Elizabeth's Windsor Castle.

The inquest will open in Windsor town on Thursday.

Police said there was no sign of a struggle and the 67-year-old's death on Saturday was "consistent with hanging", suggesting he might have killed himself.

Berezovsky was the kingmaker behind Vladimir Putin's ascent to power in Russia, but later became his number-one enemy and fled to Britain in 2000.

Berezovsky's associates have hinted he was depressed after losing a $6bn court case against another tycoon, Roman Abramovich, last year, when a judge humiliated him publicly by saying he was an unimpressive and unreliable witness.

Other people close to him have said they were not convinced by the official account.

"If he really hanged himself why was that not known from the very beginning?" said Andrei Sidelnikov, an opposition figure who knew Berezovsky.

"I don't believe it was a suicide."

Kremlin 'godfather'

In Russia, state media quoted Deputy Prosecutor General Alexander Zvyagintsev as saying the government would continue efforts to "bring back assets that Berezovsky and his accomplices acquired criminally and legalised abroad".

Mass-circulation tabloid Komsomolskaya Pravda, which supports the Kremlin, ran a front page headline on Wednesday that read: "Did Berezovsky hang himself or did he have help?"

A master of political manipulation, Berezovsky had been known as the "Godfather of the Kremlin" and wielded immense influence during a decade that followed the Soviet collapse.

Once a mathematician with Nobel Prize aspirations, he built a massive business empire under former president Boris Yeltsin and was the first of Russia's so-called oligarchs.

He then became one of the first victims of a political crackdown of the early Putin era after falling out with his protege.

Once in exile, Berezovsky often said he feared for his life, particularly after the fatal poisoning of his friend and former Russian spy Alexander Litvinenko with a dose of the radioactive isotope polonium-210 in London in 2006.

Another friend and business partner, Badri Patarkatsishvili, also died in unclear circumstances two years later.

Berezovsky survived an assassination attempt in 1994 when a bomb exploded in his car, decapitating his driver.

In his final months he led a much less extravagant life.

He suffered another blow in 2011 when he was forced to pay one of Britain's biggest divorce settlements to his former wife Galina. Media reported the settlement topped $100m.