WASHINGTON - North Korea's Internet has gone dark amid rumours of US retaliation over its alleged hacking of a Hollywood studio, just as the pariah state came under attack at the UN over its rights record.
It was not clear who or what had shut down Pyongyang's web connections, but cyber experts said the eccentric dictatorship's already limited connections had gone completely offline.
And, in an unconnected development that nevertheless piled further pressure on Kim Jong-Un's hermit regime, UN members debated North Korea's brutal treatment of his huge prison population.
"North Korea is completely off the Internet," Earl Zmijewski, vice president of data analytics at respected cyber security firm Dyn Research, told AFP on Monday.
Pyongyang's disappearance from the web came after US President Barack Obama vowed to retaliate for what the FBI said was North Korea's cyber assault on Hollywood studio Sony Pictures.
US officials refused to confirm or deny that Washington was behind the North's Internet outage.
But they called for compensation for Sony which -- following threats against movie-goers -- pulled the Christmas Day debut of comedy "The Interview," which lampoons North Korean leader Kim Jong-Un.
"If they want to help here they could admit their culpability and compensate Sony for the damages that they caused," State Department deputy spokeswoman Marie Harf told reporters.
Dyn Research said earlier Monday that Internet connectivity between North Korea and the outside world, never good at the best of times, had begun to show signs of instability over the weekend.
"This is different from short duration outages we have seen in the past," said Zmijewski in an email to AFP.
But he stressed it was impossible to say what had caused the outage. "They could have elected to simply pull the plug or they could have suffered from some sort of failure or attack," he said.
"I wouldn't be surprised if they are absorbing some sort of attack presently," Doug Madory, the director of Internet analysis at Dyn, had earlier told the North Korea Tech website.
North Korea's communist authorities have denied being behind the Sony hacking that also led to the release of a slew of embarrassing company emails.
Instead, Pyongyang has called for a joint investigation, and vowed reprisals if the US brings in new sanctions, including putting the country back on the list of state sponsors of terrorism.
The diplomatic row comes as China failed on Monday to block the first-ever UN Security Council meeting on North Korea's dismal rights record after a strong majority of members voted in favour of it.
US ambassador Samantha Power -- backed by envoys from Britain, Australia and France -- said North Korean citizens experience a "living nightmare" or political repression.
And she recalled testimony from a starving prison camp survivor who picked kernels of corn from cattle dung to eat and of a former guard who said prison wardens routinely raped prisoners.
Power dismissed Pyongyang's offer of a joint investigation into the hack was "absurd" urging the council to take action against North Korean leaders.
No decision was taken on Monday on the call to refer North Korea to the International Criminal Court for crimes against humanity, but human rights advocates urged the body to keep the issue alive.
North Korea, one of the most repressive nations on the planet, has limited access to the worldwide web, with just four networks on the global Internet, compared to 150,000 in the United States.
All of North Korea's routing is done through China Netcom, which is now part of China Unicom, Zmijewski said.
Washington has urged Beijing -- Pyongyang's closest ally -- to help rein in the North's cyber hacking activities, with US Secretary of State John Kerry speaking with Chinese Foreign Minister Wang Yi over the weekend to discuss the problem.
"As North Korea's sole Internet provider, it would be easy for China Unicom to disable North Korea's access," Zmijewski added.
"We have checked from hosts inside of China Unicom's network and can confirm that North Korea is not visible from within China either."
Pyongyang's main Internet presence is through its Uriminzokkiri website, which has Twitter and Flickr feeds and is best known for posting propaganda videos excoriating South Korea and the United States.