North Korean state media has been "unusually silent" on the health or whereabouts of its leader Kim Jong-un after a day of intense international speculation sparked by media reports claiming he was gravely ill.

Daily NK, a website based in Seoul, South Korea, reported late on Monday that Mr Kim was hospitalised on 12 April, hours before a cardiovascular procedure.

However, the English-language version of the report, which has not been confirmed, said the story was based on a single unnamed source in North Korea.

State media has presented a “business as usual” image, with routine reporting on Mr Kim’s supposed achievements and some of his older, or undated, comments on issues.

Mr Kim’s name was plastered all over the official Rodong Sinmun newspaper as usual, but there were no reports on his whereabouts.

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

Meanwhile, South Korean and Chinese officials, along with sources familiar with US intelligence, have cast doubt on media reports claiming Mr Kim is seriously ill.

Donald Trump, who held summits with the North Korean leader in 2018 and 2019, said he did not put much credence in the reports.

“We’ll see how he does,” Mr Trump told a White House news conference on Tuesday.

“We don't know if the reports are true.”

A spokesperson for South Korea's presidential Blue House said they could not confirm Mr Kim's whereabouts, or whether he had undergone surgery, and added South Korea had detected no unusual activity in its neighbouring country.

Speculation about the North Korean leader’s health was first sparked by his absence from the anniversary of the birthday of the country’s founding father and Mr Kim’s grandfather, Kim II Sung, on 15 April.

The Daily NK report claimed Mr Kim’s health had deteriorated since August due to heavy smoking, obesity and overwork, and said he was now receiving treatment at a villa in the Mount Myohyang resort north of the capital of Pyongyang.

“It does look like something is going on, based on the repeated absences of last week,” Chad O’Carroll, CEO of the Korea Risk Group, said.

“A health issue seems to be the most logical explanation for all this, but whether or not it's cardiac-related seems to be too early to tell.”

Other North Korea experts have cautioned that it is difficult to find hard facts on Mr Kim’s condition, but noted that his absence at major celebrations for his grandfather’s birthday signalled something was wrong.

Thae Yong-ho, a former North Korean deputy ambassador to the UK who defected to South Korea in 2016, said the state media's extended silence was unusual because it had been quick to dispel questions about the status of its leadership in the past.

“Every time there is controversy about [Mr Kim], North Korea would take action within days to show he is alive and well,” he said in a statement.

His absence from the 15 April anniversary ceremony, in particular, was “unprecedented”, Mr Thae said.