Kim Jong Un slams 'criminal' warship launch accident in rare public rebuke

North Korean leader Kim Jong Un has condemned a warship launch accident as a "criminal act" and demanded the vessel be restored before a key political meeting next month.

According to the state-run KCNA news agency, the 5,000-tonne destroyer – one of the largest warships ever built by the North – capsized during its launch at a port in Chongjin, in the country's northeast.

The accident reportedly crushed parts of the hull and caused the ship to lie on its side in the water.

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"Kim Jong Un made stern assessment saying that it was a serious accident and criminal act caused by absolute carelessness, irresponsibility and unscientific empiricism which is out of the bounds of possibility and could not be tolerated," KCNA reported.

The report said the incident was caused by a loss of balance while the vessel was being launched and that "sections of the bottom of the warship were crushed," but it did not mention whether there were any casualties.

Kim Jong Un said the accident "brought the dignity and self-respect of our state to a collapse", and added that restoring the destroyer was "not merely a practical issue but a political issue directly related to the authority of the state".

South Korea's military said the warship was lying sideways in the water after the failed launch.

"The intelligence authorities of South Korea and the United States had been monitoring the activities in advance," said Lee Sung-jun, spokesperson for South Korea's Joint Chiefs of Staff.

Later on Thursday, the South Korean military said North Korea had fired multiple cruise missiles from an area south of the port where the failed launch occurred.

A similar destroyer launch in April at the west coast shipyard of Nampho was also attended by the North Korean leader.

The 5,000-tonne destroyers launched this year are the largest warships built by North Korea to date.

A report published last week by US-based monitoring group 38 North said satellite imagery suggested the ship was likely side-launched from the quay.

"The use of this launch method could be one of necessity, as the quay where the ship is being built does not have an incline" to move the vessel stern first into the water, the 38 North report said.

Commercial satellite imagery taken the day before the launch showed the destroyer positioned on the quay, with support vessels by its side and its missile tube magazines exposed.