A South Korean official has said that Kim Jong-un’s absence from the public eye suggests “he has not been working as normal”, amid mounting speculation that the North Korean leader has fallen ill.

Although the South Korean government has dismissed rumours regarding Mr Kim’s health, insisting on Sunday that he is “alive and well”, questions persist.

Yoon Sang-hyun, chairman of the foreign and unification committee in South Korea’s National Assembly, told a gathering of experts on Monday the leader’s prolonged absence indicated “he has not been working as normal”.

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

Speculation over Mr Kim’s health began after he failed to make a public appearance at a key state holiday on 15 April, and has since remained out of sight.

Kim Jong-un: Power in pictures Show all 20 1 /20 Kim Jong-un: Power in pictures Kim Jong-un: Power in pictures Kim Jong-un rides a horse during snowfall in Mount Paektu in this image released by North Korea's Korean Central News Agency on 16 October 2019 Reuters Kim Jong-un: Power in pictures Kim Jong-un visits the newly built Pyongyang Orphans' Primary School on 2 February 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects a women's company under Unit 5492 of the Korean People's Army in November 2019 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects the test-fire of intercontinental ballistic missile Hwasong-14 at an undisclosed location in July 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un celebrates the successful test-fire of the intercontinental ballistic missile Hwasong-14 at an undisclosed location in July 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects a potato at the Samjiyon Potato Factory in North Korea in October 2018 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un rides a horse through a forest in this image released by North Korea's Korean Central News Agency on 16 October 2019 EPA Kim Jong-un: Power in pictures Kim Jong-un inspects a block of frozen fish at a processing facility in North Korea in November 2018 Reuters Kim Jong-un: Power in pictures Kim Jong-un celebrates the succeful launch of a strategic submarine-launched ballistic missile in August 2016 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un shakes hands with Donald Trump as they meet for the first time at the Capella Hotel on Sentosa island in Singapore in June 2018 Reuters Kim Jong-un: Power in pictures Kim Jong-un and Donald Trump share a glance as they meet in the Demilitarised Zone in Panmunjon, Korea in June 2019 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects mushrooms at Pyongyang Mushroom Farm AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects a super-large multiple rocket launcher ahead of a test in September 2019 Reuters Kim Jong-un: Power in pictures Kim Jong-un inspects an apple farm in South Hwanghae Province in September 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects an apple farm in South Hwanghae Province in September 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects dental wares at a newly built factory in June 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un visits Farm No 1116 in September 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un visits a motor factory in November 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un rides a horse during snowfall in Mount Paektu in this image released by North Korea's Korean Central News Agency on 16 October 2019 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects the Command of the Strategic Force of the Korean People's Army at an undisclosed location in August 2017 AFP/Getty

Reuters claimed that China had sent a team of medical experts to advise on Mr Kim last Thursday, days after a report by the Seoul-based Daily NK newspaper cited an anonymous source who claimed the leader had undergone heart surgery.

South Korea media has also reported that the leader, believed to be 36-years-old, may be in isolation to avoid exposure to the coronavirus – though North Korea says it has no confirmed cases of Covid-19.

Addressing the fervent speculation, a senior foreign policy adviser to South Korean president Moon Jae-in said there was nothing “suspicious” about Mr Kim’s recent movements.

“Our government position is firm,” Chung-in Moon told Fox News. “Kim Jong Un is alive and well. He has been staying in the Wonsan area since 13 April. No suspicious movements have so far been detected.”

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.

Mr Chung-in’s suggestion that the North Korean leader may be staying out of Pyongyang was lent further credence on Saturday by satellite images published by 38 North, a website specialising in North Korea studies.

The pictures showed a train likely belonging to Mr Kim parked at his Wonsan compound on the country’s east coast since at least 21 April. It had not been present on 15 April, the website’s researchers said.

“The train’s presence does not prove the whereabouts of the North Korean leader or indicate anything about his health, but it does lend weight to reports that Kim is staying at an elite area on the country’s eastern coast,” they added.

Mr Kim’s health is of crucial importance due to concern that the serious illness or death of a leader venerated by many North Koreans could cause instability in the impoverished, nuclear-armed country.

While North Korea makes it virtually impossible for outsiders to determine what is happening at senior levels within the country, South Korea’s main spy agency also has a mixed record on confirming developments north of the border.

Few outsiders knew of Kim Jong-il’s death in December 2011 until it was reported by North Korea’s state media two days later.

On Sunday, North Korean state newspaper Rodong Sinmun reported that Mr Kim had sent his gratitude to workers who contributed to the construction of the city of Samjiyon.

Continuing speculation over Mr Kim’s healths comes as the South Korean government said that it will seek “realistic and practical ways” for cooperation with North Korea upon the second anniversary of the Panmunjom Declaration.

The declaration, which outlined efforts to end the Korean conflict and move towards denuclearisation of the peninsula, was signed by Mr Moon and Mr Kim during their first summit on 27 April 2018, at the inter-Korean border village of Panmunjom.