Japanese public broadcaster NHK has issued an apology after sending a news bulletin that incorrectly reported North Korea had launched a missile that fell into waters east of the Japanese archipelago.

Key points: The information was sent on NHK's website and delivered to users' phones shortly after midnight

The information was sent on NHK's website and delivered to users' phones shortly after midnight The details contained in the alert were similar to a 2017 missile launch made by North Korea

The details contained in the alert were similar to a 2017 missile launch made by North Korea The alert came among heightened tensions due to a North Korean warning of a possible "Christmas gift" for the USA

The news alert came as the United States and its East Asian allies were on tenterhooks after Pyongyang's warning this month of a possible "Christmas gift" for Washington in what experts took to mean a possible long-range missile test.

The NHK bulletin, which was sent out 22 minutes after midnight on its website, read: "North Korean missile seen as having fallen into seas about 2,000 km east of Hokkaido's Cape Erimo", suggesting a flight path over Japanese territory.

The same information was also delivered to users' phones through NHK's apps.

NHK corrected the information on those platforms, as well as on television and radio, within half an hour, an NHK spokesman said.

"We apologise to our viewers and the public," NHK said in a statement on its website, explaining the alert was for training purposes.

It also said it would review its procedures to prevent a recurrence.

NHK News sent an apology 23 minutes after sending the original alert saying a North Korean missile had fallen into the sea east of Hokkaido. ( Supplied )

Warning citizens about disasters and security threats is one of the mandates for the publicly funded broadcaster, whose newscasters regularly and frequently hold drills for earthquakes and other disaster coverage.

When North Korea did launch missiles that flew over Cape Erimo in Japan's far north in 2017, warnings spread through sirens and government-issued "J-alerts" on millions of cell phones throughout Japan, jolting some out of sleep.

NHK had also sent an erroneous news alert about a North Korean missile in error in January of last year.

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Vipin Narang, an associate professor of political science at MIT who researches nuclear proliferation, warned this type of mistake could escalate tensions.

"At this particular moment, a false alarm like this can start a war," he wrote on Twitter.

A mistaken emergency alert about a long-range missile sparked panic among Hawaii residents in January 2018 before officials apologised for an employee who pushed the "wrong button".

North Korean leader Kim Jong-un had given the United States until the end of the year to propose new concessions in talks over his country's nuclear arsenal and reducing tensions between the adversaries.

Its last test of an intercontinental ballistic missile was in November 2017, when it fired a Hwasong-15, the largest missile it has ever tested. Pyongyang said the missile was capable of reaching all of the United States.

ABC/ Reuters