A major accident occurred at a launch ceremony for a new North Korean naval destroyer, state media KCNA reported on Thursday, with leader Kim Jong-un saying the mishap was a "criminal act".

At a ceremony to launch a new 5,000-tonne destroyer in the eastern port city of Chongjin on Wednesday "a serious accident occurred," the Korean Central News Agency said.

Blaming "inexperienced command and operational carelessness" during the launch, which was being observed by Kim, KCNA said there was a mishap that left "some sections of the warship's bottom crushed".

It said the accident managed to "destroy the balance of the warship."

Kim watched the entire incident and declared it a "criminal act caused by absolute carelessness," warning it "could not be tolerated".

He said the "irresponsible errors" of officials responsible would be "dealt with at the plenary meeting of the party central committee to be convened next month".

Kim said the accident "brought the dignity and self-respect of our state to a collapse", adding an immediate restoration of the destroyer was "not merely a practical issue but a political issue directly related to the authority of the state."

Pyongyang unveiled another 5,000-tonne destroyer-class vessel named Choe Hyon last month.

North Korea said the vessel was equipped with the "most powerful weapons" and that it would "enter into operation early next year".

In March, Kim inspected a project to build a nuclear-powered submarine, asserting that "radically" boosting the navy was a key part of Pyongyang's defensive strategy.

Kim called at the time for the modernisation of the country's surface and underwater naval forces, including the development of warships. (Agencies)