Leon Panetta warned of "exceptionally grave damage" to US security
CIA Director Leon Panetta has warned that releasing certain documents on the interrogation of al-Qaeda suspects would gravely damage US security.
Mr Panetta made the submission in court papers presented to a US federal judge on Monday.
The CIA chief argued that releasing CIA information describing the tough interrogation methods used would reveal too much to America's enemies.
Civil liberties activists have brought a lawsuit seeking the details.
Dozens of cables
Legal action has already led to the unveiling of memos issued by the former Bush administration which authorised harsh interrogation methods such as simulated drowning - known as water-boarding.
But the CIA is trying to prevent the release of further documents including dozens of cable communications.
These describe in detail the methods used against terror suspects and what information was obtained from them.
In his submission to the court, Mr Panetta wrote: "I have determined that the disclosure of intelligence about al-Qaeda reasonably could be expected to result in exceptionally grave damage to the national security by informing our enemies of what we knew about them, and when, and in some instances, how we obtained the intelligence."
The CIA chief also acknowledged that the CIA destroyed 92 video tapes of detainee interrogations which took place in 2002.
Officials have already said that some of the tapes showed the "enhanced interrogation techniques", which critics of the measures regard as torture.
A criminal investigation is underway into why they were destroyed.
Last month the CIA turned down a request by former Vice-President Dick Cheney to release secret documents as part of a campaign to show that harsh interrogation techniques had yielded key intelligence.
President Barack Obama is also attempting to block a court decision ordering the release of photos showing American troops abusing prisoners - reversing a previous decision to allow them to be published.
Mr Obama said last month he feared that publication would further inflame anti-American feelings in Iraq and Afghanistan