U.S. investigating more than 150 UBS clients for possible tax evasion

— -- More than 150 wealthy American customers of Swiss banking giant UBS are under investigation for suspected tax evasion, federal prosecutors disclosed Tuesday.

The glimpse at the scope of the much-watched criminal probe of Americans who may be hiding offshore assets from the IRS came in a Florida federal court filing as UBS prepares to give federal authorities the names of more U.S. clients who will likely face similar tax investigations.

That handover, expected as early as Wednesday, is expected to "produce the identities and account information of additional UBS customers who are believed to have violated United States law," Acting U.S. Attorney Jeffrey Sloman said in the court filing.

Tax lawyers for UBS clients said they expect the bank will provide data for thousands of its American account holders — but not for all of the estimated 52,000 U.S. customers the IRS demanded in a federal court lawsuit. The handover stems from a settlement reached in the case last week by UBS and the Justice Department.

The 150 Americans now targeted by prosecutors are among roughly 250 U.S. clients of UBS whose account information the bank gave to the Justice Department earlier this year because their accounts bore potential signs of tax evasion.

Along with providing the financial data, UBS agreed to pay $780 million to defer prosecution of criminal charges that it routinely sent its bankers on secret trips to the U.S. to help American customers hide assets offshore.

So far, three of the clients whose accounts were included in the initial UBS handover have pleaded guilty to filing tax returns that falsely failed to report millions of dollars in assets or income. A fourth is scheduled to plead guilty next month to charges of failing to report a UBS account allegedly used to evade taxes on more than $1 million in business income.

In all four cases, the UBS clients disguised their ownership of the secret accounts by controlling them through entities in Hong Kong, Panama or the British Virgin Islands, federal court records show.