LONDON: Syrian billionaire Rami Makhlouf, who is a cousin of President Bashar Al-Assad, has been denied access to undisclosed sums of money in his Swiss bank accounts after losing an appeal to the country’s Federal Court.

Swiss bank accounts belonging to Makhlouf, who has close ties to the Syrian government and is considered to be the country’s wealthiest businessman, were frozen in 2011 after he was placed on a Swiss Federal Court sanctions list, the Swissinfo news site reported.

On Friday, Switzerland’s highest court upheld an earlier decision taken in June 2015 by the Federal Administrative Court to reject Makhlouf’s appeal to unfreeze his account on the basis that there is “highest probability that Makhlouf is close to the Syrian government and that there is a risk of financial support to the Syrian government.”

Makhlouf, a maternal cousin of President Assad, conducts much of his business through associates and is subject to international sanctions in numerous countries, including the US, where he was described in diplomatic cables as Syria’s “poster boy for corruption.”

In an effort to clean up his image after being vilified by opponents of Assad’s rule, he has separated himself from some of his business interests in Syria and portrayed himself as the main donor to a foundation for orphans and widows.

However Swiss authorities say this does not prove he has separated himself from the Syrian government. "The defendant has a personal and direct interest in maintaining the current regime if he wants to keep his status and his way of life," the Federal Administrative Court said in 2015.

Details unearthed by the Panama Papers revealed that The Makhlouf family was said to be worth $5 billion before the war in Syria and had control of up to 60 percent of the Syrian economy, with interests in duty free, retail, banking and telecommunications.

In 2013, Makhlouf’s brother, Hafez Makhlouf, head of the Syrian secret service, was refused an entry visa application to Switzerland and had his assets in the country frozen, alongside those of his father Mohamad Makhlouf.