WikiLeaks founder Julian Assange has slammed the movie based on the birth of his secret-leaking website, insisting it's doomed to bomb in the box office.

Since the film's inception, the WikiLeaks editor-in-chief has been critical of the project, and just days after the letter he wrote to Benedict Cumberbatch, urging him to quit The Fifth Estate, was posted on his whistleblowing site, he's now campaigning hard against the film's upcoming release later this month (Oct13).

Speaking out against the controversial film in an interview with reporters from the Hollywood Foreign Press Association, he is forthright about his distaste for the film, which he deems inaccurate and a "hostile endeavor".

Assange insists, "The movie is destined to be a box-office failure. Audiences prefer combative underdog stories."

He goes on to blast the bosses at Dreamworks, the studio behind the film, for not even consulting him or other employees of WikiLeaks regarding the movie.

Assange adds, "I don’t think we are in a situation anymore where an organisation like DreamWorks or Disney can succinctly decide that it is going to produce a movie about living people, and living political refugees, and people who are embroiled in a grand jury proceeding in the United States, and just smear, without the cost."

Assange has been living at the Ecuadorean embassy in London for more than a year after he was given political asylum there. He faces immediate arrest and extradition to Sweden to face accusations of rape and sexual assault if he leaves the building.