North Korea has hailed the cyberattack on Sony Pictures that resulted in films being leaked online and the personal details of employees disclosed as a "righteous act".

There was speculation that the attack was carried out by North Korea as revenge for Sony's production of The Interview, which is about a fictional CIA plot to assassinate its leader, Kin Jong-Un.

The state denied carrying out the attack, rejecting it as a "false rumour" but criticised Sony for "abetting a terrorist act while hurting the dignity of the supreme leadership of the (North)".

It told the North Korean state news agency: "The hacking into the Sony Pictures might be a righteous deed of the supporters and sympathisers with the (North) in response to its appeal."

A group calling itself Guardians of Peace claimed responsibility for the attack, in which the details of 47,000 employees were hacked, and unreleased movies including Second World War drama Fury, starring Brad Pitt, were leaked online.

The Interview, which stars Seth Rogen and James Franco as two journalists who are roped into a plot to assassinate Kim Jong-Un, does not appear to be one of the films which has been leaked.

The social security numbers and pay details of a number of Hollywood stars is amongst the information that was stolen.

Sony has said that the attack was carried out by a well-organised group.

Security experts Kevin Mandia of FireEye Inc's Mandiant forensics unit, said in an email to Michael Lynton, chief executive of Sony Pictures Entertainment (SPE): "The scope of this attack differs from any we have responded to in the past, as its purpose was to both destroy property and release confidential information to the public."

He added: "The bottom line is that this was an unparalleled and well-planned crime, carried out by an organised group, for which neither SPE nor other companies could have been fully prepared."

The FBI has also confirmed it is investigating the attack, has warned that unknown malware may be used by hackers.