Swiss bankers are afraid to leave Switzerland for fear of arrest as the U.S. ramps up a probe into tax evaders and their accomplices abroad. Martin Naville, the head of the Swiss-American Chamber of Commerce, told Le Matin Dimanche weekly that about 1,000 Swiss bankers refuse to leave the country.

Fears have been stirred by the recent arrest of several high-profile Swiss bankers overseas, including former UBS (NYSE: UBS) head of wealth management Raoul Weill, who was apprehended on Oct. 19 while vacationing in Italy, AFP said Monday. Swiss banks are cautioning employees about leaving for vacations or business.

Under old Swiss bank secrecy laws, banks in the country accepted billions of dollars in undeclared assets from U.S. citizens, although they have halted this practice because of a probe by U.S. authorities. According to a U.S. federal grand jury indictment, Weil and others hid around $20 billion from U.S. tax authorities, an amount equal to about 15 billion euros.