North Korea has detained three people over an accident that occurred during the launch of a new warship this past week, state media reported early on Sunday.

Pyongyang has said that “a serious accident occurred” at Wednesday’s launch ceremony in the eastern port city of Chongjin for a newly built 5,000-tonne naval destroyer, in which sections of the bottom of the vessel were crushed.

The North Korean leader, Kim Jong-un, called the mishap a “criminal act caused by absolute carelessness”.

He said the accident damaged the country’s dignity and vowed to punish those found responsible.

Those detained are Kang Jong Chol, the chief engineer at the Chongjin shipyard; Han Kyong Hak, head of the hull construction workshop; and Kim Yong Hak, deputy manager for administrative affairs, the Korean Central news agency (KCNA) reported.

The KCNA report said the three were “responsible for the accident”.

On Friday, KCNA reported that shipyard manager Hong Kil Ho had been summoned by law enforcement.

Kim has ordered the ship to be restored before a ruling party meeting in June. KCNA said the rehabilitation plan was pushing ahead.

South Korea’s military said US and Seoul intelligence authorities assessed that North Korea’s “side-launch attempt” of the ship failed, and the vessel was left listing in the water.

KCNA, however, reported that an “underwater and internal inspection of the warship confirmed that, unlike the initial announcement, there were no holes made at the warship’s bottom”, calling the extent of the damage “not serious”.

Satellite imagery shows the warship, covered in blue tarpaulins, lying on its side, with the stern swung out into the harbour, but the bow remaining on the side slipway, according to the US-based Center for Strategic and International Studies.

Based on its size and scale, the South Korean military said the newly built warship is believed to be similarly equipped to the 5,000-tonne destroyer-class vessel Choe Hyon, which North Korea launched last month.

Pyongyang has said the Choe Hyon is equipped with the “most powerful weapons”, and that it would “enter into operation early next year”.

Seoul’s military has said the Choe Hyon could have been developed with Russian help, possibly in exchange for Pyongyang deploying thousands of troops to help Moscow fight Ukraine.

Analysts say the warship involved in Wednesday’s accident may have also been constructed with Russian assistance.