North Korea has arrested a fourth official following last week's failed launch of a new navy warship, North Korean state media reported on Monday.

The accident on Wednesday crushed parts of the bottom of the new 5,000-ton destroyer.

The official Korean Central News Agency (KCNA) reported Monday that a fourth person, Ri Hyong Son, the vice department director of the Munitions Industry Department of the Party Central Committee, had been detained.

According to KCNA, he was "greatly responsible for the occurrence of the serious accident."

He is the most senior official to be detained in connection with the incident.

His detention came after three shipyard officials — the chief engineer, the head of the hull construction workshop and deputy manager for administrative affairs — were detained on Sunday, according to KCNA.

Satellite images showed Pyongyang's second known naval destroyer lying on its side in the water at the northeastern port of Chongjin covered in a blue tarp.

KCNA said Monday that "work for completely restoring the balance of the warship is being actively conducted."

Kim condemns criminal 'carelessness'

Pyongyang has said no "serious" damage was caused. On Friday, North Korea said it would take 10 days for repairs to be completed, but observers in South Korea say it could take a lot longer.

The incident has been viewed as an embarrassing setback for North Korea and its leader Kim Jong Un, who wants to strengthen the isolated regime's naval forces to counter US influence in the region.

Kim was present for the launching ceremony on Wednesday. He has called the incident a "criminal act caused by absolute carelessness, irresponsibility and unscientific empiricism."

North Korea's first destroyer was launched last month. State media reports said it is capable of carrying a variety of weapons, including nuclear missiles.

Edited by: John Silk