A false alarm about a North Korean missile was issued in Japan overnight.

Japan's public broadcaster has apologised for claiming North Korea had launched a ballistic missile on the country.

It comes just days after a similar incident in Hawaii, but unlike the American state, the alert was corrected in a matter of minutes.

However, CNN's Paula Hancock said it was taken seriously, because Japan is used to North Korean missiles flying over the country.

"There have been J-alerts over recent months in Japan. This is an alert for when North Korea has fired a missile over the top of Japan or a ballistic missile heading in that direction."

Despite the quick resolution, Hancock said it still caused plenty of concern.

"We've been able to see people running for cover and underground so certainly there would be residents that would be concerned about this, but it was a very quick correction from this broadcaster."