Shares in Switzerland's largest bank, UBS, fell to a new all-time low on Monday after the lender's top executives met with a barrage of criticism for the way they handled a U.S. probe into tax fraud.

UBS agreed last week to pay a $780 million fine and disclose the identity of about 300 of its U.S. clients to avert criminal charges it was facing under the U.S. investigation.

The settlement was backed by the Swiss government, but experts said it opened cracks in Switzerland's treasured bank secrecy laws, and UBS is still facing a civil case in which U.S. authorities are seeking access to the names of another 52,000 clients.

Market sentiment toward UBS has reached a clear low. The weakening of bank secrecy and the negative press following it continue to keep the stock and the bank's top management under heavy pressure, said a Switzerland-based trader.

Shares in UBS were down 3.1 percent at 10.66 Swiss francs at 0944 GMT (4:44 a.m. EST), just above a low of 10.50 Swiss francs hit earlier on Monday. This compared to a 3 percent rise in the Dow Jones index of European bank stocks <.SX7P>.

Swiss newspapers were full of criticism of UBS Chairman Peter Kurer and Chief Executive Marcel Rohner at the weekend.

A UBS spokesman rejected reports on Sunday that suggested that Kurer and Rohner had been aware of illegal offshore structures, saying neither U.S. nor Swiss authorities were accusing them of this.

Stocks of other Swiss private banks were also under pressure. Private bank EFG , which is due to publish results on February 25, was down 6.6 percent after hitting its lowest level since its stock market listing in 2005.

Bank Sarasin , which is publishing results on February 26, was down 3.9 percent. Credit Suisse was down 0.66 percent.

Shares in bank Vontobel , another Swiss private bank, bucked the negative trend and were up 0.86 percent.

(editing by John Stonestreet)