Switzerland is examining whether it can assist in the request, said Folco Galli of the Swiss federal prosecutor's office on Sunday. Further details of the request have not been released.
The U.S. Department of Justice and the financial regulatory body, the Securities and Exchange Commission, are investigating services provided by Swiss-based UBS staff to American clients between 2000 and 2007 and whether the bank itself helped clients evade taxes.
A former UBS executive is due to appear before a court in Florida on Thursday charged with conspiring to defraud the U.S. by helping wealthy clients hide assets and evade taxes.
Switzerland negotiated a deal with the U.S. in 2001 that allowed its banks to manage the wealth of American clients on U.S. soil only if they named such individuals to the tax authorities.
UBS has said that it is cooperating with investigations and will address any issues raised.