"This dispute is of course an important issue for UBS," Mr Roth was quoted as saying. "But the bank has taken measures to reduce the risks. UBS today is a well-capitalized bank. We have no doubt that the bilateral dispute will be solved," Mr Roth said.

UBS, which has already agreed to pay $780 million in fines to settle charges that it helped wealthy US citizens evade taxes, has moved to shut offshore bank accounts for US citizens. It is, however, refusing to hand over details on thousands of clients to the US authorities. Up to 52,000 client accounts could be disclosed, although it was reported this week that US officials have found that far fewer accounts are involved than the 52,000 figure.

Earlier this week, Swiss government officials said they would refuse to let UBS transfer client data as this will breach Swiss bank secrecy laws.