Washington, D.C. ? The Internal Revenue Service on Friday warned of Internet scam artists trying to obtain people’s bank account numbers and other information by posing as a participant in a program offering free tax preparation software to low- and middle-income taxpayers.

The tax agency said in a statement that the IRS Web site, www.irs.gov, is the only way to access the Free File program, and that taxpayers should avoid other Web sites claiming to be part of the program.

The tax agency said it was looking into allegations that the bogus Web sites, which were not identified, were accepting tax information from taxpayers, then changing the taxpayers’ bank account numbers to their own and filing the return through a legitimate Free File partner.

Free File is a partnership between 19 tax software companies and the IRS that provides free software to taxpayers with an adjusted gross income of $52,000 or less.

The tax agency says 95 million out of 136 million taxpayers qualify for the program, which debuted in 2003, although use is relatively small. Everson said that as of April 5, almost 3.1 million people had used Free File, down more than 4 percent from last year.