The IRS has effectively halted its investigation of Lois Lerner’s missing e-mails to avoid interfering with an inspector general’s investigation, Internal Revenue Service Commissioner John Koskinen told lawmakers Wednesday on Capitol Hill.

The IRS chief’s tesimony, at his third hearing this month before the House Oversight and Government Reform Committee, came a  day after House Republicans said the hard drive of Lerner, a former IRS official, was less damaged than the agency let on and that backup tapes containing her missing e-mails may still be available.

IRS Commissioner John Koskinen testifies on Capitol Hill in Washington on July 23. (AP Photo)

MORE: Wait, Lois Lerner’s missing e-mails may still be available?

The committee’s Republicans released testimony Tuesday showing that IRS Deputy Associate Chief Counsel Thomas Kane told congressional investigators that the agency is no longer certain whether it recycled all of the backup tapes containing Lerner’s e-mails.

Koskinen said he has not examined how Kane determined some tapes might still exist. “I agreed with [the inspector general’s office] that they would do the investigation, we wouldn’t do anything to interfere with that — I wouldn’t, and none of our people would, talk to anybody about it,” he said.

Koskinen told Congress at a hearing last month that Lerner’s missing communications could not be recovered because the IRS had erased and then recycled her hard drive after it crashed in June 2011.

The committee’s Republicans expressed skepticism and frustration with the commissioner Wednesday. “People cite ongoing IG investigations when it suits them not to cooperate, and they don’t cite competing IG investigations when it doesn’t suit them,” said Rep. Trey Gowdy (R-S.C.).

Republicans on the House Ways and Means Committee said Tuesday that they learned that Lerner’s hard drive was only “scratched” and that the data was potentially recoverable. They said the IRS ignored in-house advice to seek outside help to retrieve the information.

“If the IRS would just come clean and tell Congress and the American people what really happened, we could put an end to this,” House Ways and Means Committee Chairman Dave Camp (R-Mich.) said in a statement on Tuesday. “Our investigators will not stop until we find the full truth.”

Rep. Elijah Cummings (Md.), the ranking Democrat on the House oversight committee, said Wednesday that Koskinen has become “collateral damage” in a fight for attention between the chairmen of the two committees.

“This is unseemly,” Cummings said. “It’s embarrassing, and it is not a proper way to run an investigation or to spend millions of dollars in taxpayer funds.”

Lerner oversaw the agency’s tax-exemption division, which was at the center of the IRS targeting controversy. An inspector general last year released a report that said the division has targeted nonprofit groups for extra scrutiny based on their names and policy positions.