SEOUL (KOREA HERALD/ASIA NEWS NETWORK) - North Korean leader Kim Jong Un's health is in relatively good condition, though he has a family history of diabetes and high pressure, according to lawmakers briefed by South Korea's spy agency.

The National Intelligence Service (NIS) has used 3-D video analysis designed to monitor changes in a person's body to check Mr Kim's condition for years, its official told lawmakers at a briefing to the parliamentary intelligence committee earlier this week.

The NIS is also analysing a soil sample collected from near North Korea's major nuclear site Punggye-ri, which it dismantled in the presence of international journalists in May, according to the lawmakers.

"The NIS has asked outside experts to look into soil that was collected right after North Korea shut down the nuclear test site on May 24," a lawmaker was quoted as saying by Yonhap News Agency.

North Korea invited international inspectors to verify the dismantling of the nuclear site, where the reclusive country conducted all six of its nuclear tests, during US Secretary of State Mike Pompeo's visit to Pyongyang, apparently to defy criticism that the shutdown was only for show.

"It seems to take time to analyse the soil sample," another lawmaker was quoted as saying. "The NIS is expected to work with not only local experts but also foreign intelligence agencies."