The man who oversaw the raid that killed Osama bin Laden, ex-CIA director Leon Panetta, vouched Friday for "Zero Dark Thirty," calling it a "good movie" even though the tale of the biggest manhunt in history had to be simplified for the big screen.

"It's a movie," Panetta said, laughing. "And it's a good movie. But I lived the real story," he told AFP in an interview.

Panetta, who is due to step down as US defense secretary this month, said the film should not be seen as a historical account of the secret operation that he was intimately involved with as the head of the CIA from 2009 to 2011.

"It's a little tough for me to take everything I saw and all of the work that was done and that was involved in that operation... and all of the people that worked at it and think you could put that all into a two-hour movie. You really can't."

But Panetta indicated that the Oscar-nominated film did convey some sense of the years of legwork it took the CIA to track down the Al-Qaeda mastermind to a hideout in Pakistan.

"I think people ought to make their own judgments. There are parts of it that give you a good sense of how the intelligence operations do work. But I also think people in the end have to understand that it isn't a documentary, it's a movie."

The film, starring Jessica Chastain as a relentless CIA officer, suggests that torture and abuse of some suspects helped generate information that led to the May 2011 raid that ultimately took out bin Laden.

The portrayal has sparked criticism from some senators, rights advocates and even the acting head of the CIA, Michael Morell.

But Panetta said harsh interrogation methods, including water boarding or simulated drowning, did play a role in locating bin Laden, though not a decisive one.

"The whole effort in going after bin Laden involved 10 years of work, in piecing together various pieces of intelligence that were gathered. And there's no question that some of the intelligence gathered was a result of some of these methods," he said.

"But I think it's difficult to say that they were the critical element. I think they were part of the vast puzzle that you had to put together in order to ultimately locate where bin Laden was."

Asked if the Al-Qaeda leader would have been discovered even without the interrogation methods widely condemned as torture, Panetta said: "I think we would have found him, even without that piece of the puzzle."

The CIA and the Pentagon cooperated heavily with the filmmakers, who were given access to officials and even offered a meeting with a Navy SEAL commando familiar with the raid.

Panetta declined to offer a critique of how he was portrayed on screen by Hollywood star James Gandolfini.

"Somebody came up to me and said I saw you in that movie but you lost a lot of weight," he joked.

And Panetta, who often speaks of his Italian immigrant parents, said he was grateful the actor chosen to play him shared his Italian-American heritage.

"You know, I'm glad that it was an Italian."