SEOUL (REUTERS) - There are no signs North Korean leader Kim Jong Un has received heart surgery when he disappeared from state media for three weeks, but he reduced public activity due to coronavirus concerns, South Korean lawmakers briefed by the spy agency said on Wednesday (May 6).

Mr Kim attended the completion of a fertiliser plant, North Korea's official media said on Saturday, the first report of his appearing in public since April 11.

His absence fuelled a flurry of speculation about his health and whereabouts, with a South Korean news outlet reporting Mr Kim was recovering from a cardiovascular procedure while CNN said US officials were monitoring intelligence he was "in grave danger" after surgery.

Members of South Korea's parliamentary intelligence committee said after a meeting with the National Intelligence Service (NIS) that the reports were "groundless."

"The NIS assesses that at least he did not get any heart-related procedure or surgery," committee member Kim Byung-kee told reporters.

"He was normally performing his duties when he was out of the public eye. At least there's no heart-related health problem."

But the lawmaker said Mr Kim Jong Un only made 17 public appearances so far this year, compared with an average of 50 from previous years, which the NIS ascribed to a possible coronavirus outbreak in North Korea.

"Kim Jong Un had focused on consolidating internal affairs such as military forces and party-state meetings, and coronavirus concerns have further limited his public activity," Mr Kim Byung-kee said.

"Though North Korea maintains it has zero cases, it cannot be ruled out that there is an outbreak there given they had active people-to-people exchanges with China before closing the border in late January."

North Korea has said it has no confirmed cases.

South Korea's Unification Minister Kim Yeon-chul, who oversees North Korea affairs, has said Mr Kim's public disappearance was not particularly unusual because the country had been taking stringent steps to head off an outbreak.

The lawmaker said Mr Kim Jong Un had ordered measures to prevent the disease, stabilise prices and strengthen military discipline, as border shutdowns and market closures prompted rises in food prices and panic-buying in the capital Pyongyang.

Mr Kim's visit to the fertiliser factory appeared to be aimed at expressing his resolve to ease food shortages and build a self-reliant economy, Mr Kim Byung-kee noted.