Seoul, Oct 28 (IANS): North Korean leader Kim Jong-un has lost around 20 kg after previously weighing about 140 kg, but he appears to have no health issues, South Korea's spy agency said on Thursday.

The National Intelligence Service (NIS) gave the briefing during a closed-door parliamentary session, rejecting rumours that the communist regime was using a stand-in for Kim during recent public appearances, Rep. Kim Byung-kee of the ruling Democratic Party told reporters.

The NIS made the assessment after conducting a detailed study of the North Korean leader's health using artificial intelligence and other scientific methods, Yonhap News Agency quoted the lawmaker as saying.

Kim's health has been a frequent subject of speculation due to the political implications in the event that he is unable to perform his duties.

No known successor has been appointed.

The NIS also reported North Korea could have reprocessed spent nuclear fuel rods at its main nuclear complex in Yongbyon from February to July.

By reprocessing spent fuel rods, the North can harvest weapons-grade plutonium.

Kim has also removed portraits of his father and grandfather, former leaders Kim Jong-il and Kim Il-sung, from the backdrop of official meetings, the agency said.