WASHINGTON — The Obama administration said Thursday that it needs two more months to review an internal CIA report on the agency's secret detention and interrogation program before making it public, drawing criticism from civil libertarians who say it's past time for Americans to know how its government treated terrorism suspects.

The Justice Department had originally said it intended to release the report in June as part of a lawsuit, but department officials now say they need until the end of August.

The report by the CIA's inspector general questioned the effectiveness of harsh interrogation methods employed by CIA interrogators during the Bush administration, such as waterboarding, which simulates drowning.

The American Civil Liberties Union, which has sued for release of the report, said it's time for President Barack Obama to live up to his promises of greater transparency and release the report instead of making further delays.

"The public has a right to know what took place in the CIA's secret prisons and on whose authority," said Jameel Jaffer, director of the ACLU National Security Project.

Justice Department spokeswoman Tracy Schmaler said the report contains information that overlaps with other CIA documents that they also must review and release by a court-ordered Aug. 31 deadline.

"As we re-reviewed the CIA IG report it was clear that we would not be able to complete it in an expedited manner as we had hoped," Schmaler said. "There are unique processing issues to this review that made it clear to us we would need all the time the court gave us to complete it."

The government published a version of the report in 2008, but its contents were almost entirely blacked out. The ACLU filed a Freedom of Information Act lawsuit for release of all documents related to the interrogation program.

On June 3, a federal judge gave the administration until Aug. 31 to release 319 documents related to the program, but the Justice Department initially said it would expedite review of the inspector general report and turn it over in June. The report, more than 200 pages long, had been expected to be made public two weeks ago but was held back over debates about how much of it should be censored.

Justice Department attorneys said in a letter to U.S. District Judge Alvin K. Hellerstein that they are not able to expedite the release of the report because they first need to review the other 318 documents to determine what needs to be redacted.

"Given the sensitivity of the information at issue, and the need for coordination among multiple components of the government, the review of the remanded documents is a time-consuming and labor-intensive exercise," the government attorneys wrote.

The ACLU wrote Hellerstein saying it objects to further delay of the report's release.

"It is apparent that the CIA report is not being delayed for legitimate reasons but to cover up evidence of the agency's illegal and ineffective interrogation practices," said ACLU attorney Amrit Singh. "It is time for the president to hold true to his promise of transparency and once and for all quash the forces of secrecy within the agency. The American public has a right to know the full truth about the torture that was committed in its name."