Mystery surrounds the death of Russian oligarch Boris Berezovsky after the coroner recorded an open verdict at his inquest.

The Jewish-born businessman was thought to have killed himself while suffering from depression after he lost £3billion in damages to Chelsea Football Club owner Roman Abramovich,

But coroner Peter Bedford was unable to conclude whether the death was caused by suicide or murder after forensic pathologist Professor Bernd Brinkmann cast doubt on the evidence.

Prof Brinkmann, who had been retained by Mr Berezovsky's family, said marks on the deceased's neck were not consistent with those of someone who had hanged himself.

He believed that the businessman had been strangled and then hung from the shower rail.

Mr Berezovsky was one of several Jewish oligarchs in the Kremlin inner circle during Boris Yeltsin’s presidency and was key in the election of Vladimir Putin.

He became a fierce critic of Mr Putin and sought political asylum in the UK after surviving two assassination attempts.

The 67-year-old multi-millionaire was found dead on the bathroom floor in his Ascot home with a ligature around his neck last year. The original Home Office post-mortem concluded that it was a suicide.

The hearing at Windsor Guildhall heard how Mr Berezovsky was clinically depressed and often talked of committing suicide after losing his legal claim against Mr Abramovich in August 2012.