The actions could be prompted by the ongoing trial in Miami of ex-UBS banker Bradley Birkenfeld, who admits helping clients to conceal around $20 billion in order to dodge income tax.
Yesterday, federal prosecutors called on the Miami judge to allow tax authorities to force the bank to give up the clients' personal information - a process known in legal circles as a "John Doe" summons.
If the judge acquiesces, which seems likely, the names will only not be made public if the clients pay up.
Speaking to the news agency, offshore banking expert Jack Blum said: "If I were advising clients, I'd tell them to come clean; the people who come clean early will probably be allowed to get off with paying the tax, the interest and the penalties.
"Others could very easily face criminal prosecution.''