Pyongyang denies responsibility for cyber-attack and threatens grave consequences if Washington continues to blame it

North Korea has proposed holding a joint inquiry with the US into the hacking of Sony Pictures, claiming it can prove it did not carry out the cyber-attack.

The foreign ministry in Pyongyang denied responsibility for the the highest-profile corporate hack in history, and said there would be grave consequences if Washington refused to collaborate on an investigation and continued to blame it.

The state KCNA news agency added that claims North Korea had conducted the attack on Sony in revenge for the controversial comedy The Interview, a multimillion-dollar comedy starring James Franco and Seth Rogen that depicts the assassination of Kim Jong-un, were “groundless slander”.

KCNA quoted the foreign ministry as saying: “As the United States is spreading groundless allegations and slandering us, we propose a joint investigation with it into this incident.

“Without resorting to such tortures as were used by the CIA, we have means to prove that this incident has nothing to do with us.”

North Korea’s comments came after Barack Obama said Sony had made a mistake in axing the comedy, which had been due for release on Christmas Day.

Speaking on Friday after the FBI pinned the blame for the cyber-attack on North Korea, Obama said: “We cannot have a society in which some dictator some place can start imposing censorship here in the United States, because if somebody is able to intimidate folks out of releasing a satirical movie, imagine what they start doing when they see a documentary that they don’t like, or news reports that they don’t like.

“Or even worse imagine if producers and distributors and others start engaging in self-censorship because they don’t want to offend the sensibilities of somebody whose sensibilities probably need to be offended.

“That’s not who we are. That’s not what America is about.”

Obama said he was sympathetic to Sony’s plight but added: “I wish they had spoken to me first.”

Sony Entertainment’s CEO, Michael Lynton, hit back, saying the company had been in touch with White House officials over the hacking before the film was pulled.

Lynton argued the comedy had been pulled because it would have been impossible to screen after major cinema groups backed out for fear of terrorist attacks.

Lynton told CNN he hoped the film would still be shown, but added no video on demand services had supported a release.

“We have not backed out. We have always had every desire to let the American public see it,” Lynton said.