Zuercher Kantonalbank calls time on U.S. clients-paper

* Bank told U.S.-based customers it was closing their accounts

* ZKB is part of a broader U.S. investigation into Swiss banks

ZURICH Jan 5 (Reuters) - Swiss regional bank Zuercher Kantonalbank told U.S. customers it was closing their accounts, a Swiss newspaper reported, as the bank, embroiled in a U.S. tax investigation into Swiss banks, pulls back from the risky offshore business.

"The cantonal bank is giving its customers 60 days to name a new bank where ZKB can transfer their assets," Tages-Anzeiger said on Thursday, adding account holders who reside in the U.S. had been informed by letter before Christmas.

The largest of Switzerland's part or wholly state-owned cantonal banks, which already pulled out of part of its U.S. offshore business in 2009, is then going to liquidate the accounts, the newspaper reported.

The bank was not immediately available to comment.

ZKB, one of eleven banks that U.S. justice officials allege helped wealthy Americans evade taxes through hidden offshore accounts, said last month it was cooperating with U.S. authorities.