North Korea suffered a new Internet outage today shortly after calling US President Barack Obama a "monkey" over the release of a comedy film about a fictional plot to kill its leader.



The latest shutdown came after the isolated dictatorship's powerful National Defence Commission (NDC) threatened "inescapable deadly blows" over the film and accused the US of "disturbing the Internet operation" of media outlets after a blackout earlier this week.



The cause of the outages of the country's already limited Internet access has not been confirmed.



The earlier shutdown triggered speculation that US authorities may have launched a cyber-attack in retaliation for the hacking of Sony Pictures -- the studio behind The Interview -- which Washington said Pyongyang was behind.



The outage today evening also affected telecommunication networks in the pariah state, according to Chinese state-run Xinhua news agency.



"At Pyongyang time 7:30 pm (1030 GMT) North Korea's Internet and mobile 3G network came to a standstill, and had not returned to normal as of 9:30 pm," Xinhua said, adding that its reporters in the North found the Internet to be "very unstable" throughout the day.



Respected cyber security firm Dyn Research said the Internet blackout was "country-wide".



"This time there wasn't the hours of routing instability that presaged the outage like last time. Although it did flicker back on for a moment, and go back down and stay down," said Doug Madory, director of Internet Analysis with Dyn Research.



"If an outside force took it down again, it did it more efficiently than the previous incident."



The firm later said the Internet was back, tweeting: "Off-again, on-again: North Korea returns after 5 hour national outage."



The North has about one million computers -- mainly at educational and state institutions -- but most lack any connection to the world wide web.



All online content and email are strictly censored or monitored with Internet access limited to a handful of top party cadres, propaganda officials and expatriates.



The NDC accused Obama of taking the lead in encouraging cinemas to screen The Interview on Christmas Day. Sony had initially cancelled its release after major US cinema chains said they would not show it, following threats by hackers aimed at cinemagoers.



"Obama always goes reckless in words and deeds like a monkey in a tropical forest," a spokesman for the NDC's policy department said in a statement published by the official KCNA news agency.

