South Korea's spy agency says North Korea has punished two top military officers during a highly unusual inspection of the military's powerful political bureau.

The office of South Korean lawmaker Kim Byung-kee says Seoul's National Intelligence Service provided the information during a closed-door parliamentary briefing Monday.

Kim's office cited the spy agency as saying the inspection, the first of its kind in 20 years, occurred because of an unspecified “impure” attitude in the North Korean military's political bureau.

The spy agency told lawmakers the head of the bureau, Hwang Pyong So, and his top deputy were punished. It was unclear whether they were verbally warned, dismissed or banished to a rural area.

South Korea's spy agency has a spotty record in reporting developments in North Korea.