Hollywood studio Sony has been forced into a fresh defence of the controversial film Zero Dark Thirty, about the hunt for Osama bin Laden, after a member of the body that organises the Oscars called for a boycott.

Academy of Motion Picture Arts and Sciences (Ampas) member David Clennon said last week he would not be voting for Kathryn Bigelow's film, which has been nominated for five Oscars, and urged others to snub a movie that he said "promotes the acceptance of the crime of torture, as a legitimate weapon in America's so-called War on Terror". Writing on the truth-out.org website, he added: "I cannot vote for a film that makes heroes of Americans who commit the crime of torture."

In response, Sony president Amy Pascal said she was "outraged" that an Academy member would try to influence the voting process. "Zero Dark Thirty does not advocate torture," she said on Friday. "To not include that part of history would have been irresponsible and inaccurate. We fully support Kathryn Bigelow and [screenwriter] Mark Boal and stand behind this extraordinary movie. We are outraged that any responsible member of the Academy would use their voting status in Ampas as a platform to advance their own political agenda."

While Zero Dark Thirty remains in the running for five Oscars, it already appears to have slipped behind frontrunners such as Steven Spielberg's Lincoln and Ang Lee's Life of Pi owing to the ongoing controversy over whether Bigelow and Boal endorsed torture by their depiction of its use in the film, and whether that depiction was accurate. Bigelow surprisingly failed to receive a nod for best director when the Oscar nominations were announced on Thursday, and Zero Dark Thirty will compete only for best film, best original screenwriting, best actress (Jessica Chastain) and two editing prizes.

The furore over the film, which also stars Jason Clarke and Joel Edgerton, seems to have had a more positive effect on its potential profitability, however. Zero Dark Thirty went to No 1 at the US box office at the weekend with $24m. Bigelow and Boal's previous film, the multiple Oscar-winning The Hurt Locker, took just $17m throughout its entire US box-office run, despite the Academy's accolades.

The controversy showed no sign of letting up over the weekend as an ex-CIA agent, Lindsay Moran, publicly questioned why photographs of Bin Laden's dead body have not yet been released by the CIA when Zero Dark Thirty's depiction of the hunt for the al-Qaida leader would most likely – in her opinion – do far more to radicalise potential terrorists.

"Zero Dark Thirty is an amazing movie, but very revealing about the entire hunt for Osama bin Laden," she said. "It contains a lot of disturbing scenes of detainees being tortured." Speaking on US TV show The Young Turks, Moran added: "What I find ironic is the government claiming that this is classified information and would put Americans at risk at the very same time that two Hollywood film-makers were given unprecedented access to the CIA – basically made an infomercial about CIA interrogation."

Meanwhile, actor Martin Sheen and former president of the Screen Actor's Guild, Ed Asner, were named as the latest Hollywood figures to join Clennon's boycott, according to the LA Times. "One of the brightest female directors in the business is in danger of becoming part of the system," Asner was quoted as saying.