China condemns cyberattacks, but does not mention North Korea

China has said it opposes all forms of cyberattacks, but it stopped short of directly condemning the hacking of Sony Pictures, or of responding to U.S. calls for action against North Korea, blamed by Washington for the assault.

Chinese Foreign Minister Wang Yi "reaffirmed China's relevant position, emphasising China opposes all forms of cyberattacks and cyber terrorism" in a conversation with U.S. Secretary of State John Kerry on Sunday, the foreign ministry in Beijing said in a statement.

"(China) opposes any country or individual using other countries' domestic facilities to conduct cyberattacks on third-party nations," it said.

The statement made no direct mention of North Korea.

China is North Korea's only major ally, and would be central to any U.S. efforts to crack down on the isolated state. But the United States has also accused China of cyber spying in the past and a U.S. official has said the attack on Sony could have used Chinese servers to mask its origin.

South Korea, which is still technically at war with North Korea, said on Monday that computer systems at its nuclear plant operator had been hacked and non-critical data stolen, but there was no risk to nuclear installations or reactors.

"It's our judgement that the control system itself is designed in such a way and there is no risk whatsoever," Chung Yang-ho, deputy energy minister, told Reuters by phone.

He made no mention of North Korea and could not verify messages posted by a Twitter user claiming responsibility for the attacks and demanding the shutdown of three ageing nuclear reactors by Thursday.

U.S. President Barack Obama and his advisers are weighing how to punish North Korea after the FBI concluded on Friday that Pyongyang was responsible for the attack on Sony.

It was the first time the United States had directly accused another country of a cyberattack of such magnitude on American soil and set up the possibility of a new confrontation between Washington and Pyongyang.

North Korea has denied it was to blame and has vowed to hit back against any U.S. retaliation.

"We do not know who or where they (the hackers) are but we can surely say that they are supporters and sympathisers with the DPRK," said a commentary on KCNA, the North's state news agency. DPRK, or the Democratic People's Republic of Korea, is the official name for the North.

"Our toughest counteraction will be boldly taken against the White House, the Pentagon and the whole U.S. mainland, the cesspool of terrorism, by far surpassing the 'symmetric counteraction' declared by Obama," it said.

Japan, one of Washington's closest allies in Asia, said it strongly condemned the attack on Sony Pictures, but also stopped short of blaming North Korea.

"Japan is maintaining close contact with the United States and supporting their handling of this case," Chief Cabinet Secretary Yoshihide Suga told a regular news conference.

He did not answer when asked if Japan was convinced North Korea was behind the cyber attack, but repeated that he saw no effect on talks with North Korea over the fate of Japanese citizens abducted by Pyongyang agents decades ago.

OBAMA PONDERS OPTIONS

Obama put the hack in the context of a crime.

"No, I don't think it was an act of war," he told CNN's "State of the Union" show that aired on Sunday. "I think it was an act of cyber vandalism that was very costly, very expensive. We take it very seriously. We will respond proportionately."

Obama said one option was to return North Korea to the U.S. list of state sponsors of terrorism, from which Pyongyang was removed six years ago.

The hack attack and subsequent threats of violence against theatres showing the film prompted Sony to withdraw a comedy, "The Interview," prepared for release to movie theatres during the holiday season. The movie depicts the fictional assassination of North Korean leader Kim Jong Un.

Obama and free speech advocates criticized the studio's decision, but Sony Pictures Entertainment CEO Michael Lynton defended it, saying U.S. theatres did not want to show it.

In the CNN interview, which was taped on Friday, Obama acknowledged that in a digitised world "both state and non-state actors are going to have the capacity to disrupt our lives in all sorts of ways."

"We have to do a much better job of guarding against that. We have to treat it like we would treat, you know, the incidence of crime, you know, in our countries."

Republican Senator John McCain disagreed with Obama, telling CNN the attack was the manifestation of a new kind of warfare.

Republican Representative Mike Rogers, chairman of the House Intelligence Committee, would not call the hacking an act of war. But he did criticise Obama for embarking on a two-week vacation in Hawaii on Friday without responding to the attack.

"You've just limited your ability to do something," Rogers said. "I would argue you're going to have to ramp up sanctions. It needs to be very serious. Remember - a nation-state was threatening violence."