WASHINGTON (Reuters) - The Central Intelligence Agency thought for months that it had mistakenly shredded a massive U.S. Senate report on its use of waterboarding and other “enhanced interrogation techniques” before suddenly discovering that its copy had not been lost after all, an agency official said on Tuesday.

The lobby of the CIA Headquarters Building in McLean, Virginia, August 14, 2008. REUTERS/Larry Downing

“It’s embarrassing and I have apologized,” Christopher Sharpley, the acting CIA Inspector General, told the Senate Intelligence Committee during his confirmation hearing as President Donald Trump’s nominee for the position.

Championed by Democratic Senator Dianne Feinstein when she chaired the Senate panel, the “torture report,” as it is known, is the result of a six-year investigation into so-called enhanced interrogation techniques used by the CIA after the Sept. 11, 2001, attacks, during the administration of Republican President George W. Bush.

The report has been the subject of disputes between the agency and committee Democrats, as well as Democrats and Republicans, over issues including whether it should be declassified and whether investigators broke the law as they assembled it.

Feinstein wants the 6,700-page document declassified. But Republican Senator Richard Burr, her successor as committee chairman, has resisted its release and asked for the return of copies distributed to government agencies under Democratic President Barack Obama.

Sharpley said the CIA received the report in December 2014 on a computer disk, which was then uploaded into a classified system. Shortly thereafter, he said, the agency was told to delete it because of ongoing Freedom of Information Act (FOIA) litigation.

An email was sent saying the disk should not be destroyed, but Sharpley said he was told months later it could not be found and that an employee said it had been shredded.

But he said the disk was discovered later, after the FOIA litigation concluded that the report was a “congressional” document not subject to FOIA requests.

DEMOCRATS FRUSTRATED

Sharpley said around that time, Burr asked him to return the disk and he did so.

The committee’s Democrats appeared frustrated by Sharpley’s account.

“The point of distributing it to the departments was in the hope that they would read it - not look at it as some poison document - and learn from it,” Feinstein said, noting that to her knowledge, not a single fact in the report has been refuted.

Sharpley said he had not read the report, only an unclassified executive summary.

Democratic Senator Ron Wyden announced after the hearing that he would not support Sharpley’s nomination because he had handed the report over to Burr, although there was no legal requirement to do so.

Sharpley also would not commit to protecting any future reports, such as one related to the committee’s probe of potential links between Trump’s campaign and Russian efforts to interfere in the 2016 U.S. election.

“I think your highest duty here is to follow the law. The notion that the chairman asked for it and that’s all that governed your judgment isn’t acceptable to me,” Wyden said during the hearing.

Obama ended the use of “enhanced interrogation techniques” via executive order in January 2009. Led by Feinstein and Republican Senator John McCain, Congress has since passed legislation outlawing their use.

Burr said he planned a vote on Sharpley’s nomination next week and looked forward to supporting him.