Georgian tycoon Badri Patarkatsishvili died of natural causes at his Leatherhead home.

A postmortem examination on the billionaire - who had feared he had been targeted for assassination by the Georgian Government - showed he died of heart failure.

Mr Patarkatsishvili collapsed and died in front of his wife at their £10million mansion at 11pm on Tuesday.

The scene was reportedly tested for radioactivity but investigators found no evidence of radioactive materials being involved in Mr Patarkasishvili's death.

Mr Patarkatsishvili had led and paid for an opposition campaign against Georgian President Mikhail Saakashvili.

In January Mr Patarkatsishvili ran against Saakashvili in a snap election - which opposition groups allege was rigged - and gained around seven per cent of the vote.

He had been seen in Georgia as a driving force behind anti-Government protests in November and left the country - spending time in Israel and Britain - while being investigated on charges of plotting to overthrow the Government.

The businessman was friends with Kia Joorabchian, a leading sports agent who represents Manchester United's Carlos Tevez, and tried to buy West Ham Football Club a couple of years ago.

In December Mr Patarkatsishvili had told Associated Press he had a recording of a Georgian interior ministry official asking a Chechen warlord to murder him.