Washington ? Federal investigators on Monday expanded a tax evasion inquiry involving offshore bank card schemes to include records from Visa. They also announced that MasterCard has turned over 1.7 million records the IRS is using to target people with audits and criminal prosecution.

In addition, the Justice Department and Internal Revenue Service announced that American Express Co. has agreed to release records in the investigation, which officials estimate could eventually involve up to 2 million U.S. citizens who have credit or debit cards issued by foreign banks.

“These actions should send a clear message to tax evaders,” said IRS Commissioner Charles Rossotti. “If people use these illegal offshore methods to hide their income, we will find out who they are.”

It is not against the law to have a credit card from a bank located in a tax haven country. But, using bank secrecy laws in places like the Cayman Islands and the Bahamas, a person might shield income from U.S. taxes while using a credit card issued on the account to live lavishly.

These schemes are heavily promoted in books, seminars and on the Internet. Documents filed in federal court Monday quote one author as telling would-be customers that “you can charge to your heart’s content, anywhere you want, and the information stops at your offshore bank.”

The investigation, Rossotti said, shows that “the guarantee of secrecy associated with offshore banking is evaporating.”

The IRS estimates that up to 2 million U.S. citizens hold offshore bank account cards. Officials say most of those accounts are above the $10,000 threshold requiring disclosure to the IRS, but that only 170,000 taxpayers did so in 2000 and just 117,000 in 1999.

The MasterCard International Ltd. and American Express records were sought by the government through a summons approved in October 2000. On Monday, a petition was filed in San Francisco federal court asking a judge to approve a similar summons for Visa International records.