SEOUL (AFP) - North Korean leader Kim Jung Un has sought to reassure the public over construction safety after the deadly collapse of a Pyongyang apartment building sparked a rare apology from the secretive hardline state.

Inspecting a river-side construction site in Pyongyang where two 46-storey apartment buildings are being built by soldiers, he stressed the need for quality construction in the aftermath of the May 13 accident that state media blamed on "irresponsible" supervision by officials.

The official Korean Central News Agency on Wednesday quoted Mr Kim raising the slogan: "Let us take responsibility for the safety of the project and guarantee its absolute quality for all eternity."

Mr Kim's inspection tour appeared aimed at reinforcing his regime's committment to regulate building construction after senior North Korean officials offered a rare public apology for the "unimaginable" disaster on May 13.

No death toll was given, but South Korean officials said close to 100 families were in residence at the site. The North's state media said Kim "sat up all night, feeling painful" after being told about the accident.

About 2.5 million people - mostly the ruling elite or those considered politically trustworthy - live in Pyongyang and enjoy priority access to electricity, food and other goods and services.

The North in 2009 announced plans to build 100,000 new high-rise apartments in its showpiece capital. Students and soldiers were drafted in to help complete the project on time.

Mr Kim - since taking power after the death of his father Kim Jong Il in Dec 2011 - has launched a flurry of high-profile construction projects of his own.

He last year celebrated the opening of a new water park, an equestrian club and apartments for scientists, teachers and athletes in the capital, and a massive ski resort in the northeast.