SEOUL: South Korean officials are emphasising that they have detected no unusual movements in North Korea and are cautioning against reports that North Korean leader Kim Jong Un may be ill or is being isolated because of coronavirus concerns.

At a closed-door forum on Sunday, South Korea's Unification Minister Kim Yeon-chul, who oversees engagement with the North, said the government has the intelligence capabilities to say with confidence that there were no indications of anything unusual.

Rumours and speculation over the North Korean leader's health began after he failed to make a public appearance at a key state holiday on April 15, and has since remained out of sight.

South Korea media last week reported that Kim may have undergone cardiovascular surgery or was in isolation to avoid exposure to the coronavirus.

Unification Minister Kim cast doubt on the report of surgery, arguing that the hospital mentioned did not have the capabilities for such an operation.

Still, Yoon Sang-hyun, chairman of the foreign and unification committee in South Korea's National Assembly, told a gathering of experts on Monday that Kim Jong Un's absence from the public eye suggests "he has not been working as normally".

"There has not been any report showing he's making policy decisions as usual since April 11, which leads us to assume that he is either sick or being isolated because of coronavirus concerns," Yoon said.

North Korea has said it has no confirmed cases of the new coronavirus, but some international experts have cast doubt on that claim.

South Korea's President Moon Jae-in vowed on Monday to step up cooperation to help the North prevent the spread of the coronavirus but made no mention of Kim's health or whereabouts.

"I will find a path for the most realistic and practical inter-Korean cooperation," Moon told a meeting with senior aides, marking the second anniversary of his first summit with Kim.

"The COVID-19 crisis could mean a new opportunity for inter-Korean cooperation, and that's the most urgent and pressing task."

'ALIVE AND WELL'

On Monday, North Korean state media once again showed no new photos of Kim nor reported on his whereabouts.

However, they did carry reports that he had sent a message of gratitude to workers building a tourist resort in Wonsan, an area where some South Korean media reports have said Kim may be staying.

"Our government position is firm," Moon Chung-in, a top foreign policy adviser to South Korean President Moon, said in comments to US news outlets.

"Kim Jong Un is alive and well. He has been staying in the Wonsan area since April 13. No suspicious movements have so far been detected."

In Washington, a US official appeared to back the South Korean government officials' assessment about Kim as well as their admonition against speculation.

"That's good advice. The media should take what they're saying seriously," the official, speaking on condition of anonymity, told Reuters. However, he declined to elaborate on the US view of Kim's situation.

Kim Byung-kee, a former intelligence official and now a member of South Korea's parliamentary intelligence committee, also urged caution on speculation and said there is little possibility that Kim is ill and he would make a "surprise comeback soon."

Satellite images from last week showed a special train possibly belonging to Kim at Wonsan, lending weight to those reports, according to 38 North, a Washington-based North Korea monitoring project.

Although the group said it was probably the North Korean leader's personal train, Reuters has not been able to confirm that independently, or whether he was in Wonsan.

A spokeswoman for the Unification Ministry said on Monday she had nothing to confirm when asked about reports that Kim was in Wonsan.

Last week, China dispatched a team to North Korea including medical experts to advise on Kim Jong Un, according to three people familiar with the situation.

Reuters was unable to immediately determine what the trip by the Chinese team signalled in terms of Kim's health.

When asked about the Reuters' report on the medical team, China's foreign ministry said on Monday it has no information to offer on Kim.

On Friday, a South Korean source told Reuters their intelligence was that Kim Jong Un was alive and would likely make an appearance soon.

Experts have cautioned that Kim has disappeared from state media coverage before, and that gathering accurate information in North Korea is notoriously difficult.

North Korea's state media last reported on Kim's whereabouts when he presided over a meeting on April 11.

Kim, believed to be 36, vanished from state media for more than a month in 2014 and North Korean state TV later showed him walking with a limp.