Hollywood stars have reacted to the decision to pull a film about the assassination of the North Korean leader.

Actor Ben Stiller has described the move as "a threat to freedom of expression".

'The Interview' has been shelved after hackers threatened to launch terrorist attacks on cinemas that showed the film.

The comedy, which stars Seth Rogen and James Franco, was due to be released in the US on 25 December.

But hackers calling themselves Guardians of Peace threatened to launch attacks like those on 11 September 2001.

Sony Pictures said it was pulling the movie "in light of the decision by the majority of our exhibitors not to show the film".

Stressing that he was speaking "as a creative person, not any kind of expert", Stiller said: "Terror threats shouldn't dictate free expression. That's my opinion."

Key events in Sony cyber attack

Really hard to believe this is the response to a threat to freedom of expression here in America. #TheInterview
— Ben Stiller (@RedHourBen) December 18, 2014

Rob Lowe, who starred in the 'West Wing', also tweeted his reaction to the Sony move.

Wow. Everyone caved. The hackers won. An utter and complete victory for them. Wow.
— Rob Lowe (@RobLowe) December 17, 2014

He compared the decision to pull the film to the former British prime minister Neville Chamberlain's policy of appeasement with Adolf Hitler.

Saw @Sethrogen at JFK. Both of us have never seen or heard of anything like this. Hollywood has done Neville Chamberlain proud today.
— Rob Lowe (@RobLowe) December 17, 2014

Film-maker Michael Moore joked:

Dear Sony Hackers: now that u run Hollywood, I'd also like less romantic comedies, fewer Michael Bay movies and no more Transformers.
— Michael Moore (@MMFlint) December 17, 2014

Comedian Jimmy Kimmel branded the move an "un-American act of cowardice that validates terrorist actions and sets a terrifying precedent".

Other actors also tweeted their disapproval of the decision.

Sad day for creative expression. #feareatsthesoul
— Steve Carell (@SteveCarell) December 17, 2014

There's only one man on Earth who can solve this: pic.twitter.com/dodZXQJyzW
— Zach Braff (@zachbraff) December 17, 2014

This only guarantees that this movie will be seen by more people on Earth than it would have before. Legally or illegally all will see it.
— Judd Apatow (@JuddApatow) December 17, 2014

Sony's decision to pull THE INTERVIEW is unsettling in so many ways. Good thing they didn't publish THE SATANIC VERSES.
— Stephen King (@StephenKing) December 18, 2014

In a statement Sony Pictures said: "The studio, which has been shaken by hacker leaks over the past several weeks, said it respected and shared in the exhibitors' concerns.

"We are deeply saddened at this brazen effort to suppress the distribution of a movie, and in the process do damage to our company, our employees, and the American public.

"We stand by our film-makers and their right to free expression and are extremely disappointed by this outcome."

North Korea has denied it was behind the hacking, but security experts in Washington said it was an open secret the Pyongyang government was responsible.

"The North Koreans are probably tickled pink," said Jim Lewis, a senior fellow with the Center for Strategic and International Studies. "Nobody has ever done anything this blatant in terms of political manipulation. This is a new high."

Sony came under immediate criticism for the decision to pull the movie.

Former Republican House of Representatives speaker Newt Gingrich said on Twitter:

No one should kid themselves. With the Sony collapse America has lost its first cyberwar. This is a very very dangerous precedent.
— Newt Gingrich (@newtgingrich) December 17, 2014

The White House National Security Council said the US was investigating the Sony breach and would provide an update about who did it at the appropriate time.

"The US government is working tirelessly to bring the perpetrators of this attack to justice, and we are considering a range of options in weighing a potential response," NSC spokeswoman Bernadette Meehan said, adding that the government was not involved with Sony's decision to pull the film.

The FBI warned cinemas and other businesses associated with 'The Interview' on Tuesday that they could be targeted in cyber-attacks, according to a copy of the document reviewed by Reuters.

However, several US national security officials said the government had no credible evidence of a physical threat to moviegoers.

On Monday, Sony executives sought to reassure employees that the studio would recover from the massive cyber attack that exposed internal emails and sensitive employee data.

Unidentified hackers attacked Sony's computer network last month and have released internal documents they claim were stolen from the company.

The documents include employee salaries and financial information, marketing plans and contracts with business partners.

Actor-director Rogen has said he did not anticipate the media storm surrounding the film.

"I don't know if the hacking honestly is because of our movie, definitively or not. I know that it has been the centre of a lot of media attention lately.

"The movie itself is very silly and wasn't meant to be controversial in any way," he said.