Zurich, Switzerland (Reuters) - Swiss bank UBS sought to distance itself from a U.S. investigation of rival Swiss private banks on Thursday, saying that it did not hand over data on rival banks directly to U.S. officials when it settled a U.S. crackdown on taxpayers holding secret offshore accounts two years ago.

Several Swiss media reports have suggested since the U.S. indictment of private bank Wegelin last week, on charges that it enabled wealthy Americans evade taxes, that banks being targeted in a second wave of probes by the U.S. tax authorities were identified to U.S. officials by UBS.

The UBS settlement included disclosing data on its clients and paying a fine to avert criminal prosecution.

Since that settlement, the U.S. investigation into potential tax dodgers has spread to at least 11 other banks including Credit Suisse.

UBS said in a statement on Thursday it was required to hand over to Swiss regulator FINMA letters and other correspondence with U.S. clients, including the clients' instructions relating to winding down the accounts, where those details were available. FINMA in turn passed the data onto U.S. officials.

"Documents relating to the closing out of accounts were only available in a fraction of the roughly 4,700 cases," UBS said, adding that either clients still held accounts with UBS at the time or they had given information directly to U.S. officials or asked UBS to do so.

The U.S. uncovered a mine of information from amnesties that it offered taxpayers, parallel to the justice probe. Taxpayers with undeclared funds in offshore accounts were offered leniency for making voluntary disclosures.

(Editing by Greg Mahlich)