Aug. 5, 2009 (United Press International) -- The Internal Revenue Service wants to learn who advised wealthy Americans to evade taxes by putting their money in offshore banks, U.S. tax experts say.

Potential tax evaders who disclose their offshore holdings are being asked by federal investigators to reveal all the intermediaries who helped them establish the accounts, USA Today reported Wednesday.

The newspaper says lawyers for clients of Swiss banking giant UBS (NYSE:UBS) have provided summaries of questions that the government is asking owners, including the names of people who told them about offshore accounts, assisted in opening an account and prepared their tax returns.

"There is no question that the IRS is targeting other intermediaries," says William Sharp of Sharp & Associates, a Florida law firm representing Americans with UBS accounts.

A government program to voluntarily disclose offshore accounts before the IRS discovers them is set to expire Sept. 23.