The CIA could still be months away from approving the release of a long-awaited Senate report that is sharply critical of the agency’s use of harsh interrogation measures on terrorism suspects after the Sept. 11, 2001, attacks, according to a request the Obama administration filed in federal court Thursday.

The filing, submitted by the Justice Department, asked the court for additional time for the CIA to review the Senate report and determine how much of it can be declassified. The agency sought permission to provide a progress update on June 20, but warned that even then it would need additional time to coordinate with other agencies and possibly foreign governments before any portion of the report can be released.

The review “will likely be completed this summer, although an exact time cannot now be determined,” the Justice Department said in a motion filed in U.S. District Court in Washington in connection with a lawsuit by the American Civil Liberties Union aimed at forcing the agency to release the report publicly.

The move marks the latest delay in a Senate investigation that was launched more than five years ago. It has concluded that the CIA repeatedly misled Congress and the White House about the brutality of interrogation measures it was using, including water-boarding, and the extent to which such tactics worked.

Sen. Dianne Feinstein (D-Calif.), chairman of the Senate Intelligence Committee, said last month that she hoped key portions of the report could be declassified within 30 days.

ACLU officials said they were disappointed by the delay.

“Given how long the CIA has known about its need to make these records public, we expected something more concrete than a mere hope that declassification would take place this summer,” said Hina Shamsi, director of the ACLU’s National Security Project. “What’s also troubling is that the very agency that committed torture is the one wielding the blackout pen over what will become public.”

The full report spans more than 6,000 pages and was approved by the Senate committee on April 3. But the CIA is reviewing only the executive summary and principal findings — sections that cover about 500 pages.

President Obama, who ended the interrogation program during his first days in office, has indicated that he favors releasing as much of the document as possible to the public.

The Senate committee delivered its initial draft of the report to the CIA in December 2012. The latest filing described the updated version as “considerably longer than the prior” draft.

The agency is also reviewing other documents demanded by the ACLU as part of a Freedom of Information Act suit, including an internal report on the interrogation program commissioned by former CIA director Leon E. Panetta.

Beyond determining how much of the report can be declassified, the CIA will also have to “undertake a number of security steps to protect the safety of personnel and facilities abroad,” an apparent reference to possible protests or attacks overseas when the report is released, according to the motion.

The agency’s secret prisons were dismantled in 2009, and officials have indicated that the report will not name CIA officers or the countries where the sites were located.

The investigation has been such a source of friction between the committee and the CIA that each side has accused the other of security breaches and possible criminal misconduct.