Swiss banks probably will settle a sweeping U.S. probe of offshore tax evasion by paying billions of dollars and handing over the names of thousands of Americans who have secret accounts, Bloomberg reported.

U.S. and Swiss officials are concluding negotiations on a civil settlement amid U.S. criminal probes of 11 financial institutions, including Credit Suisse Group AG, suspected of helping American clients hide money from the Internal Revenue Service, Bloomberg said.

Switzerland, the biggest haven for offshore wealth, wants an end to new U.S. probes while preserving its decades-old tradition of bank secrecy, Bloomberg said.

Under accords the Swiss made this year with Germany and the United Kingdom on untaxed assets, the identity of clients remained secret. The United States insists that the Swiss disclose client account data, and the banks may end up handing over data on 5,000 to 10,000 accounts, Bloomberg said.

The Justice Department also may bring criminal charges or civil enforcement actions against any of the 11 financial institutions.

The U.S. crackdown against offshore tax evasion has led to charges against UBS AG, the largest Swiss bank; at least 21 foreign bankers, advisers and attorneys; and at least 36 U.S. taxpayers. UBS avoided prosecution in 2009 by paying $780 million, admitting it fostered tax evasion and handing over details on 250 secret accounts. It later disclosed another 4,450 accounts, Bloomberg said.