Our correspondent says some friends of Mr Berezovsky had said he was depressed after the failure of his legal battle in London with fellow Russian oligarch and Chelsea Football Club owner Roman Abramovich.

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He is believed to have been in serious financial difficulties after running up huge legal fees in recent years, including what was reportedly Britain's biggest-ever divorce settlement and a losing lawsuit against a former friend and ally, Chelsea football club owner Roman Abramovich.

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But he has also been criticised for buying Chelsea and not Russian football club, although Mann says it was an idea he explored.

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Helen Hart, from Illogan in Cornwall, spent the money on luxury cars, cosmetic surgery, private jet charters and a box at Chelsea Football Club.

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For Mr Abramovich, the case was simply about greed - a well paid political fixer who got well above his station and who treated the Chelsea Football Club owner like a cash cow.

BBC: Uncovered: Trial of the oligarchs

Roman Abramovich, owner of Chelsea football club, and his partner Dasha Zhukova have used Mollie Dent-Brocklehurst, whose family inhabits 15th-century Sudeley Castle in Gloucestershire, as an art adviser.

ECONOMIST: Assimilating plutocrats

Among the wealthy expected at Wood Wharf, Canary Wharf, St Katharine Docks and Royal Victoria Dock in east London are Chelsea football club owner Roman Abramovich.

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"Chelsea Football Club is obviously pleased that the Appeals Committee has vindicated the club's position and opened the door for a compensation claim and sporting sanctions before FIFA's Dispute Resolution Chamber, " the league leaders said in a statement.

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The Chelsea Football Club owner maintained that Mr Berezovsky had never owned a formal stake in his companies, and had simply been employed as a political fixer to help him make the necessary connections to build up his business empire.

BBC: Uncovered: Trial of the oligarchs