US senator Lindsey Graham said he believes North Korean dictator Kim Jong Un is “dead or incapacitated” following unconfirmed reports of his demise.

Mr Graham, an ally of Donald Trump and member of the powerful senate foreign relations committee, speculated that the hermit kingdom would not let rumours of its leader’s death go unanswered for so long.

“Well, it's a closed society, I don't know anything directly,” he said. “But I'd be shocked if he's not dead or in some incapacitated state because you don't let rumours like this go forever or go unanswered in a closed society, which is really a cult, not a country, called North Korea.”

“So I pretty well believe he is dead or incapacitated,” he told Fox News.

Rumours of Kim Jong Un’s death have swirled since he missed the commemoration of the 108th birthday of his grandfather, North Korea founder Kim Il Sung, ten days ago.

North Korean authorities have said nothing to counter media reports that Mr Kim is unwell, prompting concerns about who is next in line to run a nuclear-armed country that has been ruled by the same family for seven decades.

In pictures: Kim Jong Un goes on a Christmas tour Show all 15 1 /15 In pictures: Kim Jong Un goes on a Christmas tour In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un gives†field guidance to the August 25 Fisheries Station under KPA 313 Unit Reuters In pictures: Kim Jong Un goes on a Christmas tour korea-9.jpg Kim Jong un laughs as he inspects the August 25 Fisheries Station under KPA 313 Unit Reuters In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un stands in the August 25 Fisheries Station under KPA 313 Unit Reuters Reuters In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un arrives in the August 25 Fisheries Station under KPA 313 Unit Reuters Reuters In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un inside the August 25 Fisheries Station under KPA 313 Unit Reuters Reuters In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un visits the bier of Kim Kuk Thae, member of the Political Bureau of the Central Committee of the Workers' Party of Korea and expressed deep condolences over his death in Pyongyang Getty Images Getty Images In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un inspecting the Masik Pass Hotel, ski service and lodging buildings and rest areas in the skiing courses of the Masik Pass Ski Resort in Kangwon province Getty Images Getty Images In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un walks through the Masik Pass Hotel, ski service and lodging buildings and rest areas in the skiing courses of the Masik Pass Ski Resort in Kangwon province Getty Images Getty Images In pictures: Kim Jong Un goes on a Christmas tour North Korean leader Kim Jong Un inside a room in the Masik Pass Hotel, ski service and lodging buildings and rest areas in the skiing courses of the Masik Pass Ski Resort in Kangwon province Getty Images Getty Images In pictures: Kim Jong Un goes on a Christmas tour North Koreans gather together on the steps of Mansu Hill to lay flowers at the base of statues of the late leaders, Kim Il Sung and Kim Jong Il, in Pyongyang AP AP In pictures: Kim Jong Un goes on a Christmas tour North Korean soldiers gathered at Kumsusan memorial palace in support of their leader Kim Jong-Un in Pyongyang Getty Images Getty Images In pictures: Kim Jong Un goes on a Christmas tour North Korean People's Army soldiers take part in a rally to swear allegiance to North Korean leader Kim Jong Un ahead of the second death anniversary of former leader Kim Jong Il at the Kumsusan Palace of the Sun in Pyongyang Reuters Reuters In pictures: Kim Jong Un goes on a Christmas tour North Korean soldiers gathered at Kumsusan memorial palace in support of their leader Kim Jong-Un in Pyongyang Getty Images Getty Images In pictures: Kim Jong Un goes on a Christmas tour North Korea soldiers stand guard on the banks of the Yalu River which separates the North Korean town of Sinuiju from the Chinese border town of Dandong Getty Images In pictures: Kim Jong Un goes on a Christmas tour China has lost its key North Korean interlocutor with the purging of Kim Jong Un's uncle, but analysts say the young leader's tightening grip on power may be welcomed by Beijing, which prizes stability in its wayward nuclear-armed ally Getty Images Getty Images

Reuters reported this week that China has dispatched a team to North Korea including medical experts to advise on Kim Jong Un, citing three people familiar with the situation.

Adding fuel to the rumours, a train that likely belongs to the North Korean leader has been parked at his compound since last week, according to satellite imagery.

The satellite photos released by 38 North, a website specialising in North Korea studies, don't say anything about Kim's potential health problems, and they echo South Korean government intelligence that Kim is staying outside of the capital, Pyongyang.

"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," it said.

South Korean and US officials have repeatedly indicated that there have been no unusual signs that could indicate health problems for Kim.

A US official, speaking on condition of anonymity because he wasn't authorised to talk to the media, told Reuters the latest rumors about Kim's health had not changed the US assessment of the information as "speculation."

White House counsellor Kellyanne Conway wouldn't comment on Kim's status. "The president will make any announcement about a head of state," she said Saturday night on Fox News Channel's ‘Justice With Judge Jeannine.’