North Korea has deported or executed several officials and engineers over the deadly collapse of a new high-rise apartment building in Pyongyang, the Tokyo Shimbun daily reported Sunday.

Quoting a source in the North, the daily said four design and construction engineers were executed by firing squad and a military official in charge of the project was sent to a prison camp.

The daily said that although the exact cause of the accident remains unclear, shoddy construction is likely to blame as on-site directors and workers often siphon off steel and cement to sell on the black market.

The newspaper also reported rumors in Pyongyang that the death toll in the collapse on May 13 may be as high as 500 people.

The Yomiuri Shimbun reported that the 23-story building was inhabited by hig h-ranking intelligence and police officials. Although it had yet to be completed, 92 households had apparently moved in already.

The North Korean regime started an aggressive construction drive in the capital in 2009, but the project was plagued by a shortage of construction material, according to the Yomiuri Shimbun.

