A $600 million Supreme Court of Bermuda ruling is being challenged in London over an allegation that the Bermuda court misunderstood the business arrangement between two parties.

Reuters has reported that Georgia's former prime minister, Bidzina Ivanishvili, has urged a London court to uphold the $607 million Bermuda judgment he won against a Credit Suisse unit on the island concerning a long-running fraud committed by a former CS adviser.

The founder of Georgia’s ruling Georgian Dream party successfully sued the bank’s Bermudian life insurance arm, CS Life, seeking the return of losses caused by the rogue banker at Credit Suisse.

He not only won a $607 million judgment, but it was upheld on appeal two years ago.

Now, at the Privy Council, Credit Suisse and its new owner, UBS, are challenging the ruling.

Reuters said Charles Falconer, the CS Life lawyer, said in court filings that the Bermudian courts misunderstood its contract with Mr Ivanishvili, and the unit was “wrongly held liable for [Credit Suisse AG] failure to manage the assets”.

Reuters reported: “CS Life also referred to Ivanishvili being sanctioned by the US in December for undermining democracy for Russia's benefit, raising the question of whether Ivanishvili could be paid.

“Ivanishvili's lawyers say it would have made no sense for him to have transferred more than $750 million from Credit Suisse into two life insurance policies with CS Life, but without CS Life having any contractual obligations to him.

“Ivanishvili had separate litigation against Credit Suisse in Singapore, where he was awarded $926 million, though that sum was last year reduced on appeal to $461 million including interest and costs, according to UBS results.”