U.S. authorities have been put on high alert after the hackers responsible for stealing files from Sony Pictures' databases last month (Nov14) threatened 9/11-style attacks on movie theatres which screen Seth Rogen's controversial new comedy The Interview.

Activists calling themselves the Guardians of Peace have vowed to continue hacking into the studio giant's computers and releasing details about celebrities' salaries and personal information and whole movies, unless company bosses pull The Interview, about two Americans who set out on a mission to assassinate North Korean leader Kim Jong-un.

Over the weekend (13-14Dec14), the cyber criminals promised to go public with a new bundle of stolen material as a "Christmas gift", and they made good on their promise this week (begs15Dec14).

On Tuesday (16Dec14), the hackers stepped up its threats by promising to target any cinemas with screenings of The Interview, including its New York premiere at the Landmark Sunshine Cinema on Thursday (18Dec14).

A message released by the group reads: "The world will be full of fear. Remember the 11th of September 2001. We recommend you to keep yourself distant from the places (with screenings of The Interview) at that time. (If your house is nearby, you'd better leave.)

"Whatever comes in the coming days is called by the greed of Sony Pictures Entertainment."

However, an official for the U.S. Department of Homeland Security has played down the threats, telling Tmz.com, "We are still analyzing the credibility of these statements, but at this time there is no credible intelligence to indicate an active plot against movie theaters within the United States."

A Los Angeles screening of The Interview took place without incident last week (ends12Dec14).

Reports initially suggested officials in North Korea were responsible for the hack attack as an act of revenge over The Interview, which co-stars James Franco, and although government heads have publicly condemned the movie, they have denied any involvement in the security breach, which is being investigated by the Fbi.

Meanwhile, in light of the Guardians of Peace's latest threats, Rogen and Franco have reportedly cancelled all promotional appearances for the film ahead of its U.S. release on Christmas Day (25Dec14), according to BuzzFeed News.