19 December 2014
Last updated at 18:30
The US Federal Bureau of Investigation says North Korea was behind a cyber-attack on Sony Pictures over a film about its leader Kim Jong-un.
The agency said analysis of malware showed links to North Korea.
Sony withdrew the film The Interview following threats from hackers, who had earlier also released sensitive information stored on Sony computers.
CNN quoted the hackers as welcoming the withdrawal and warning Sony not to release the film in any form.
The emailed message was received by Sony’s top executives on Thursday night and was obtained by CNN.
US President Barack Obama is scheduled to address reporters on Friday afternoon, where he is expected to face questions on the matter.
Sony’s decision has outraged many artists. Actor George Clooney told the trade website Deadline on Thursday that the film should be released online.
Earlier the White House labelled the Sony breach a serious national security matter.
On Thursday, White House spokesman Josh Earnest told reporters US officials had held daily discussions about the Sony cyber-attack and were considering an “appropriate response”.
Sony cancelled the holiday release of the comedy film after national theatre chains refused to show it.
The movie features James Franco and Seth Rogen as two journalists who are granted an audience with North Korean leader Kim Jong-un.
The CIA then enlists the pair to assassinate him. The film was due to have been released over Christmas.
Hackers had earlier issued a warning referring to the 11 September 2001 terror attacks, saying “the world will be full of fear” if the film was screened.
The film’s cancelled release drew criticism in Hollywood, with some calling it an attack on the freedom of expression.
Actor George Clooney told the trade website Deadline on Thursday the film should be released online, saying Hollywood shouldn’t be threatened by North Korea.
North Korea says the film hurts the “dignity of its supreme leadership”
In November, a cyber-attack crippled computers at Sony and led to upcoming films and workers’ personal data being leaked online.
The hackers also released salary details and social security numbers for thousands of Sony employees – including celebrities.
North Korea earlier this month denied involvement in the hack – but praised the attack itself as a “righteous deed”.
An article on North Korea’s state-run KCNA news agency, quoting the country’s top military body, said suggestions that Pyongyang was behind the attack were “wild rumour”.
However, it warned the US that “there are a great number of supporters and sympathisers” of North Korea “all over the world” who may have carried out the attack.
In the article, Sony Pictures was accused of “abetting a terrorist act” and “hurting the dignity of the supreme leadership” of North Korea by producing the movie.