Tue Apr 29, 2014 8:26am EDT

(Reuters) - The Swiss units of Goldman Sachs Group Inc (GS.N) and Morgan Stanley (MS.N) have agreed to hand over details to U.S. authorities about how they may have helped Americans to evade taxes, the Wall Street Journal reported.

Though the two banks will not face prosecution in the United States in return, they could be penalized by up to 50 percent of the value of the undeclared U.S. accounts they have handled, the Journal said, citing people familiar with the matter. (link.reuters.com/hyp88v)

The move comes as the U.S. Justice Department ramps up its investigations of Swiss banks that helped Americans dodge taxes leading to billions of dollars of missed revenues.

As part of the program with the authorities, named category 2, banks compile information about how they set up Swiss accounts for U.S. clients and also how much was contained in the accounts, the Journal said, adding that the information must be reviewed by an independent examiner.

The Justice Department is currently probing 14 Swiss banks over taxes after UBS AG (UBSN.VX) became the first major bank to settle over the charges. Two smaller Swiss banks have had to close shop as a result of the U.S. investigation.

Last month, a former Credit Suisse Group AG (CSGN.VX) banker pleaded guilty to conspiring to help U.S. customers evade taxes by using Swiss accounts, and said he did so with the encouragement of his superiors.