Former White House aide I. Lewis "Scooter" Libby is fighting to keep his grand jury testimony about the leak of a CIA operative's name from being released and broadcast in the media.

Libby's grand jury testimony — the sworn statements he gave to investigators about his conversations with Vice President Dick Cheney and journalists — is at the heart of his perjury trial. Special Prosecutor Patrick Fitzgerald plans to play hours of recordings of that testimony in court next week to bolster his case that Libby lied and obstructed the investigation.

Trial evidence is normally public and all exhibits in Libby's case have been made public so far. Even though Fitzgerald successfully fought to get Libby's full grand jury testimony admitted into evidence, Libby's attorneys say the audiotapes should not be released outside the courtroom.

Libby defense attorney William Jeffress, who successfully argued a Supreme Court case that kept the Watergate tapes from being released, said in court Thursday that grand jury tapes are never meant to be made public.

He said he knew of no case when such recordings have been released.

In the tapes, Libby discusses conversations he had regarding CIA operative Valerie Plame, the wife of a prominent Iraq war critic. Plame's identity was leaked to reporters in 2003.

Nobody was charged with the leak. Fitzgerald said Libby learned Plame's identity from Cheney and discussed it with journalists. Libby says he forgot about his conversation with Cheney and, when he heard about Plame from a reporter weeks later, it struck him as new information.

Fitzgerald says Libby concocted that story to protect himself from prosecution because repeating rumors from reporters is less serious than repeating sensitive information from Cheney.

If the tapes are released, they could be broadcast on television news programs, radio stations and the Internet. U.S. District Judge Reggie B. Walton said he worried that would sensationalize an already public trial.

Attorneys for The Associated Press and a dozen other news organizations said they would challenge any effort to seal the tapes. Court papers were to be filed Friday afternoon. Walton said he would consider the matter over the weekend.