Swiss authorities have already handed over 500 accounts of UBS clients to the United States under an agreement to end a tax dispute that has threatened the bank's existence, a paper reported on Sunday.
The Swiss lower house rejected the agreement on Tuesday, triggering a new parliamentary debate next week and delaying a final decision on whether to allow the government to hand over a total of 4,450 UBS client accounts to U.S. authorities.
UBS , the world's second-largest wealth manager, has already handed the accounts to Swiss tax authorities but the domestic political deadlock threatens to stop Switzerland handing them on to the U.S. by the August deadline.
Missing this deadline could lead to the U.S. restarting legal action against the bank.
Around 2,900 files had already been prepared for handover and 1,550 more accounts were still being processed, Swiss paper Sonntag reported.
Client dossiers were transferred to the United States in around 500 of the 2,900 cases, the paper cited the Swiss tax office spokesman Thomas Brueckner as saying
These 500 clients had signed waivers allowing their accounts to be handed over to the U.S. taxman voluntarily. Swiss bank secrecy law usual prohibits the transfer of account details to foreign authorities.
UBS, which has asked U.S. clients to sign waivers voluntarily, declined to comment. The Swiss federal tax office was not immediately available for comment.
(Reporting by Jason Rhodes; Editing by Louise Heavens)