The court rejected an appeal by billionaire Rami Makhlouf to reverse a federal decision blocking an undisclosed amount of money in his Swiss accounts — which the government says helps "finance" and "support" al-Assad's violent regime.
Makhlouf owns 40 percent of Syria's largest mobile provider, Syriatel, and his assets in the Swiss affiliate of the British HSBC bank are estimated at around $30 million.
In an effort to clean up his image after he was vilified by opponents of al-Assad's rule, Makhlouf presented himself as the principle donor to a foundation for orphans and widows, and said he wanted to separate from the Syriatel group.
But Swiss authorities say his contribution to this foundation does not prove he has distanced himself from his cousin's reign of terror.
"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 court said.
This is not the first time that Makhlouf and his family have faced problems in Switzerland.
In 2013, the court refused an entry visa application from his brother Hafez Makhlouf, head of the Syrian secret service.