* Valiant says U.S. clients are less than 1 pct of total
* Scores more banks expected to come forward to regulator
ZURICH Dec 9 (Reuters) - Valiant Holding AG on Monday became the first Swiss bank to say it would work with U.S. officials in a crackdown on wealthy Americans evading taxes through hidden offshore accounts.
The Swiss regional bank said it would participate in the scheme brokered by the Swiss government and Washington because it could not say definitively that all its U.S. clients paid their taxes.
"The costs of the U.S. program will not jeopardize the financial stability of Valiant in any way. This decision does not endanger the distribution of an unchanged dividend," Valiant said in a statement on Monday.
Valiant is the first of what is expected to be a host of banks to tell Swiss financial regulator FINMA this week that they will bow to U.S. pressure to come clean on any past transgressions and face up to fines.
Valiant said an internal review showed it had never actively sought U.S. clients or visited Americans to drum up business. The bank said less than 0.1 percent of its clients were American.
The fines can be as much as 50 percent of assets managed on behalf of American clients depending on how egregiously the banks acted in their dealings with those customers, and would trigger a disclosure to investors because they are material to share prices.
Others being scrutinized are listed private banks such as EFG International, Vontobel, St. Galler Kantonalbank, which owns private bank Hyposwiss, Linth Bank and Banque Cantonale Vaudoise. These banks are likely to offer the first indication of how many firms the U.S. authorities can bring to cooperate because, as publicly listed stocks, they are subject to disclosure rules.
If the Swiss banks choose to shun the U.S. offer, individual firms and their senior staff risk criminal prosecution. A failure to cooperate could also hold up a settlement for around a dozen of Switzerland's largest banks, including Credit Suisse , Julius Baer, Pictet, and local government-backed Zuercher Kantonalbank (ZKB), which are under formal investigation by the U.S. Department of Justice.
In 2009, UBS, Switzerland's largest bank, was fined $780 million and agreed to hand over the names of U.S. clients with secret Swiss bank accounts to avoid facing criminal charges.