Japan's public broadcaster issued a false alarm saying North Korea appeared to have launched a missile and urging people to take shelter, but managed to correct the error within minutes.
NHK's 6.55pm (10.55pm NZT) alert on its web site said: "North Korea appears to have launched a missile... The government urges people to take shelter inside buildings or underground."
The same alert was sent to mobile phone users of NHK's online news distribution service.
In five minutes, the broadcaster put out another message on the website correcting itself and said no government warning, called "J-alert", had been issued.
"This happened because equipment to send a news flash onto the Internet had been incorrectly operated. We are deeply sorry," an NHK announcer said on its 9:00 p.m. news programme, bowing deeply in apology.
The mistake took place at a tense time in the region following North Korea's largest nuclear test to date in September and its claim in November that it had successfully tested a new type of intercontinental ballistic missile that could reach all of the US mainland.
Pyongyang regularly threatens to destroy Japan and the United States.
But there were no immediate reports of panic or other disruptions following the NHK report. A similar gaffe caused panic in the U.S. state of Hawaii at the weekend.
Last Saturday, a false missile alert during a civil defence drill caused panic across Hawaii. A state emergency management agency spokesman attributed it to human error and a lack of fail-safe measures.