A Japanese daily says that an official in charge of construction of North Korean nuclear facilities is believed to have been purged.

Quoting a North Korean defector, Japan's Asahi Shimbun reported on Tuesday that the chief of Bureau 131 of the North's ruling Workers' Party might even have been executed. 

The paper said that the bureau chief was recently removed from the post and purged for allegedly leaking military secrets. 

Bureau 131 is known to be responsible for building the North's key military facilities including portals for the Punggye-ri nuclear test site and facilities for the Dongchang-ri missile launch site. 

The report said that the official might have been purged for a delay in the North's sixth nuclear test and collapse of underground tunnels at the Punggye-ri nuclear site. 

A source said that the official was probably purged after the nuclear test scheduled for spring was delayed to September.