The Handelszeitung newspaper reported that officials leading a crackdown on suspected tax cheats received documents from UBS with information on which banks its US clients' accounts were transferred to after it was subjected to sanctions in 2009.
In a statement, UBS said it had been ordered to hand over to Swiss financial regulator Finma client data including, in some cases, instructions relating to the closure of accounts.
The bank acted according to Swiss law and the orders of the Swiss authorities, it said.
"UBS did not hand over any information on clients or banks directly to the US," the statement said.
UBS was the first Swiss bank to feel the force of Washington's clampdown on tax evasion in 2009.
The bank was forced to hand over about 4,000 files of suspected tax cheats and pay a fine of $780 million.
Bern is negotiating a tax agreement with Washington to address the issue of US nationals hiding money in Swiss accounts.
An ongoing US probe reportedly focuses on 11 Swiss banks, among them Credit Suisse, Julius Bär and Wegelin.