PYONGYANG, Dec. 27 (Xinhua) -- The Democratic People's Republic of Korea (DPRK) on Saturday rebuffed the U.S. accusation that Pyongyang was involved in a cyber attack on a Sony movie.

The United States groundlessly linked the unheard-of hacking at the Sony Pictures Entertainment to the DPRK, a spokesman for the Policy Department of the National Defence Commission of the DPRK said in a statement.

Reiterating that the DPRK has nothing to do with the hacking attacks against Sony Pictures, the spokesman urged the U.S. to conduct a joint investigation with the DPRK.

"If the U.S. is to persistently insist that the hacking attack was made by the DPRK, the U.S. should produce evidence without fail, though belatedly," the spokesman was quoted by the official KCNA news agency as saying.

Sony's new movie The Interview is an illegal, dishonest and reactionary film quite contrary to the UN Charter, which regards respect for sovereignty, non-interference in internal affairs and protection of human rights as a legal keynote, and international laws, according to the statement.

The U.S.-based Sony Pictures Entertainment was cyber-attacked in late November, which caused huge damage to the underlying system of the corporate and prompted the company to cancel the Christmas Day release of its comedy movie entitled "The Interview" which depicts an assassination attempt on top DPRK leader Kim Jong Un.

The U.S. Federal Bureau of Investigation (FBI) last week said Pyongyang was responsible for the Sony Pictures hacking, without revealing evidence because of the "protection of sensitive sources."