UPDATED 10.29AM: US President Barack Obama is warning North Korea it faces retaliation over a cyber attack on Sony Pictures, as Pyongyang continues to deny involvement.

Threats issued after the November attack prompted the movie giant to cancel the Christmas Day release of The Interview, a madcap satire about a CIA plot to kill North Korean leader Kim Jong-Un.

The anonymous hackers invoked the memory of September 11 in threatening attacks on cinemas showing the film, prompting major theatre chains to say they would not screen it.

In addition, Sony has seen the release of a trove of embarrassing emails, scripts and other internal communications.

After the FBI said Pyongyang was to blame on Friday Obama said Washington would never bow to "some dictator" but admitted he believed Sony had erred in pulling the film.

"We will respond proportionately and we'll respond in a place and time and manner that we choose," he said.

"I'm sympathetic to the concerns that they faced. Having said all that, yes, I think they made a mistake.

"We cannot have a society in which some dictator some place can start imposing censorship."

Earlier, the FBI said it had "enough information to conclude the North Korean government is responsible".

Pyongyang's mission to the United Nations, however, denies any involvement.
"Our country has no relation with the hacker," North Korean political counsellor Kim Song told news agency AFP.

The attackers used malware to break into the studio and render thousands of Sony Pictures computers "inoperable", the FBI said.

It said analysis of the software tools used revealed links to other malware known to have been developed by "North Korean actors".

It also cited "significant overlap" between the attack and other "malicious cyber-activity" with direct links to Pyongyang.

Pyongyang has repeatedly denied involvement in the brazen November 24 cyber attack but nevertheless hailed it as a "righteous deed."