North Korean authorities have made a series of rare public apologies after the collapse of an unfinished, 23-storey block of flats in Pyongyang that is believed to have killed multiple residents.

The official news agency, KCNA, said the accident happened last Tuesday and was the result of irresponsible supervision by officials in charge of the construction.

An emergency rescue effort had been carried out to rescue survivors and treat the wounded, the agency said.

The North's leader Kim Jong-un "sat up all night, feeling painful" after being told about the accident, the KCNA said.

The leader "instructed leading officials of the party, state and the army to rush to the scene, putting aside all other affairs and command the rescue operation," Kim Su-Gil, chief secretary of the city committee of the ruling Workers' Party, said in his public apology.

South Korea said the incident involved the collapse of a 23-storey apartment building, which already housed 100 families.

The KCNA did not provide a death toll or elaborate on the cause of the collapse, but did carry lengthy public apologies by senior officials including the Choe Pu-il, the minister of people's security.

"Choe repented of himself, saying that he failed to find out factors that can put at risk the lives and properties of the people and to take thorough-going measures, thereby causing an unimaginable accident," it said.

According to the KCNA report, the rescue operation ended on Saturday.

Source: Agencies