NEW YORK, April 16 – U.S. authorities on Tuesday charged a Swiss banker and a Swiss attorney with helping American clients hide millions of dollars in offshore accounts to evade paying taxes.

The case is the latest in a string of prosecutions from the Justice Department aimed at curtailing offshore tax evasion services sold by Swiss and Swiss-style banks.

Stefan Buck and Edgar Paltzer were each charged with one count of conspiracy, an indictment filed in Manhattan federal court showed. It did not name the defendants' employers.

Buck is the head of private banking and a member of the executive board at "Swiss Bank No. 1," while Paltzer is a partner at a "Swiss Law Firm" and was admitted to the New York bar in 1988, according to the indictment.

Zurich-based Bank Frey lists Stefan Buck as its head of private banking and a member of its executive board on its website.

The Swiss law firm Niederer Kraft & Frey lists Edgar Paltzer as a partner on its website, and New York state records show he was admitted to the New York bar in 1988.

Attempts to reach Bank Frey and Niederer Kraft & Frey for comment were unsuccessful outside of regular Swiss business hours.

In March 2009, Swiss bank UBS AG agreed to pay $780 million to settle charges brought by the Justice Department. The oldest Swiss bank, Wegelin & Co, pleaded guilty in January to helping wealthy Americans evade taxes and was sentenced to pay nearly $58 million in penalties.

According to the Manhattan U.S. Attorney's office, which brought the charges, Buck's bank saw an increase of 300 percent in U.S. taxpayers as clients between the time of UBS's settlement and Wegelin's indictment in February 2012.

Around $938 million, or 44 percent, of the bank's $2.1 billion in managed assets as of September 2012 was held by U.S. taxpayers, prosecutors said.

Buck and Paltzer opened and managed undeclared accounts for U.S. clients who had been informed by other Swiss banks that they had to close their accounts there.

Both men reside in Switzerland, and neither has been arrested, prosecutors said.

Paltzer, a dual U.S.-Swiss citizen, is admitted to practise law in New York, authorities said.

The defendants each face fines and a maximum prison sentence of five years.

The case is U.S.A. v Paltzer and Buck, U.S. District Court for the Southern District of New York, No. 13-282.