The special prosecutor will also look at cases that were reviewed by career prosecutors who concluded that they could not be pursued.

Bracing for the worst, a number of CIA officials have put off plans to retire or leave the agency so that they can maintain their access to classified files and be in a better position to defend themselves, the newspaper said.

'Once you're out, it gets a lot harder,' the newspaper quoted a retired CIA official as saying.

But it will also be difficult to gain criminal convictions because the quality of evidence is poor and the legal underpinnings have never been tested, the Los Angeles Times said, quoting officials with first-hand knowledge of the interrogation files.

'I don't blame them for wanting to look into it. But if they appoint a special prosecutor, it would ultimately be unsuccessful, and it would go on forever and cause enormous collateral damage on the way to getting that unsuccessful result,' the paper quoted a retired high-ranking Justice Department official as saying.

Further, any inquiry would also drive a fresh wedge between the CIA and the Justice Department, agencies with a fractious history that have struggled to work more closely together since 9/11, the newspaper said.