The Internal Revenue Service is auditing about 800 employees after discovering that a handful of its workers may have cheated on their tax returns.

"I am disappointed that a small but unacceptable number of our employees have generated false business deductions to reduce their taxes," IRS Commissioner Mark W. Everson said in a statement. "We have a zero-tolerance standard for abuse of the tax laws by employees."

The probe of employees comes during the IRS's biggest crackdown on tax cheating in more than a decade. Over the last three years, the IRS has been hiring additional agents and examiners while trying to find more efficient ways to ferret out and prosecute domestic and international tax schemes. That effort has resulted in dozens of lawsuits, indictments and settlements, making the revelation about internal misconduct all the more embarrassing.

The audits were spurred by a tip from an IRS employee that some agency workers might be filing bogus Schedule C tax forms, which are used to list profit and loss from self-employment or a small business.

After receiving the tip, the Treasury Department's inspector general for tax administration, which has oversight authority for the IRS, examined 25 IRS employee returns that included Schedule C forms and found that about half contained questionable deductions or had other compliance issues.

Several of the employees who submitted the suspect returns have been fired, IRS officials said. Some are still under investigation. The names of the employees and the offices where they worked were not released.

The tax returns of IRS employees are subject to considerably more scrutiny than the average taxpayers'. All professional-level IRS employees - from tax examiners to Commissioner Everson - are audited when they join the agency. Lower-level employees, such as typists and clerks, f01ace less-aggressive scrutiny. However, all employee returns are tagged so they can be easily sorted and reviewed if necessary, IRS officials said.