The IRS is still hiring employees it previously fired for faking resumes and abusing taxpayer data, even after being warned by Congress, according to an inspector general report made public Thursday.

The Treasury Inspector General for Tax Administration found in a report that, of the 2,000 former IRS employees the tax agency hired in 2015 and 2016, more than 200 had earlier been fired or had left amid an investigation.

Some of the workers left because of serious offenses. Four had been investigated for improperly accessing taxpayer records. Another four had cheated on their own tax returns.

Sen. Richard Burr, the North Carolina Republican who had requested the inspector general report, called the IRS' rehiring of fired workers a "mind boggling abuse of taxpayer money."

Burr also faulted IRS Commissioner John Koskinen for telling him in Senate testimony that the IRS doesn't rehire workers who were fired for performance issues.

Many congressional Republicans have sought to oust Koskinen, and some conservatives have tried to impeach him for his role in the management of the fallout from the IRS' targeting of conservative nonprofits. Koskinen's term ends in November.