Three U.S. senators who question the accuracy of the film Zero Dark Thirty are asking whether the CIA misled director Kathryn Bigelow and screenwriter Mark Boal in its briefings about the hunt for Osama bin Laden.

Sens. Dianne Feinstein, Carl Levin and John McCain are also stepping up pressure on the CIA to reveal whether coercive techniques, including torture, were effective in securing information in the hunt for the al-Qaeda leader.

Zero Dark Thirty, a fictional drama about the hunt for bin Laden, shows an al-Qaeda figure undergoing waterboarding and other abusive interrogation techniques before eventually providing information that helps track bin Laden down.

Filmmakers' contacts with CIA

The senators, part of a committee probing contacts between the filmmakers and the CIA, have criticized that scene as inaccurate, saying they had information from the agency that torture was not effective in yielding information.

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Zero Dark Thirty follows the long hunt for Osama bin Laden. U.S. senators want to know if the CIA misled the filmmakers. (Sony Columbia Pictures/Associated Press)

On Thursday, they released the text of a letter they have written to CIA acting director Michael Morell asking for the exact documents the CIA shared with the filmmakers.

Morell has admitted to meeting several times with Boal and Bigelow, but he said the movie they created is "a dramatization, not a realistic portrayal of the facts."

In their letter, the senators say they are concerned that "given the CIA’s co-operation with the filmmakers and the narrative’s consistency with past public misstatements by former senior CIA officials, filmmakers could have been misled by information they were provided by the CIA."

They also expressed dismay at a public statement posted on the CIA website stating "some [intelligence related to bin Laden’s location] came from detainees subjected to enhanced techniques, but there were many other sources as well."

Was torture effective?

The admission that intelligence may have emerged under torture contradicts the Senate Intelligence Committee's recently released report, which concluded that torture did not play a constructive role in tracking bin Laden.

The al-Qaeda leader was found in a hiding place in Pakistan and ultimately killed by U.S. Navy SEALs.

In the wake of Morell’s posted statement, the three senators sent a second letter asking Morell what information was acquired from detainees and whether it was "prior to, during, or after the detainee was subjected to the CIA’s enhanced interrogation techniques? If after, how long after?"

They also demanded access to all the documents used by Bigelow and Boal in creating the film.

"Given the discrepancy between the facts above and what is depicted in the film, previous misstatements by retired CIA officials, as well as what appears to be the CIA’s unprecedented co-operation with the filmmakers, we request that you provide the committee with all information and documents provided to the filmmakers by CIA officials, former officials, or contractors, including talking points prepared for use in those meetings," the letter read.

Should torture be shown?

Sen. McCain, who was himself tortured in Vietnam, objected to the depiction of torture in Zero Dark Thirty and has said he was concerned about the filmmakers putting forward the idea that coercive techniques were effective.

Ezat Mossallanejad, an Iranian exile who counsels torture victims in Toronto at the Canadian Centre for Victims of Torture, told CBC News he believes the film will be an education for the North American public.

"I tell you, I think I'm not unhappy about that," he said after watching the troubling scenes in Zero Dark Thirty.

"I commend the director for producing this film, because torture is surrounded by silence and secrecy. There is a circle of silence at [all] levels."

The movie has received a best picture nomination from the Golden Globes and is expected to earn Oscar nominations when they are released next Thursday.