The employee was arrested by US authorities when arriving in the country for two weeks worth of client meetings and has been banned from leaving, Swiss newspaper SonntagsZeitung reported.
A source told the news provider that the unnamed banker's arrest could be related to his previous role at Swiss bank UBS.
The employee has not yet been named while the authorities are not thought to have yet brought any charges.
A probe by the US authorities into the processes at UBS was halted last year after the bank handed over details of 4,000 UBS account holders to the Internal Revenue Services (IRS).
Doug Shulman, IRS commissioner, said at the time: âAs part of this agreement, the IRS has received approximately 4,000 UBS treaty-request accounts so far. We will get even more after the remaining account-holder appeals have been decided by the Swiss Federal Administrative Court.â
The Swiss bank avoided criminal charges in 2009 by paying a $780 million fine to regulators after admitting it helped certain account holders avoid paying tax.