North Korea said US accusations that it was involved in a cyberattack on Sony Pictures were "groundless slander" and that it was wanted a joint investigation into the incident with the United States.

An unnamed spokesman of the North's foreign ministry said there would be "grave consequences" if Washington refused to agree to the joint probe and continued to accuse Pyongyang, the official KCNA news agency reported on Saturday.

On Friday, President Barack Obama blamed North Korea for the devastating cyberattack, which led to the Hollywood studio cancelling "The Interview", a comedy on the fictional assassination of North Korean leader Kim Jong Un.

In its first substantive response to the accusation, the isolated North Korea said it could prove it had nothing to do with the massive hacking attack.

"We propose to conduct a joint investigation with the US in response to groundless slander being perpetrated by the US by mobilizing public opinion," the North Korean spokesman said.

"If the US refuses to accept our proposal for a joint investigation and continues to talk about some kind of response by dragging us into the case, it must remember there will be grave consequences," the spokesman said.-Reuters