Fear of catching the coronavirus could have kept North Korean leader Kim Jong-un away from state ceremonies for a key holiday in mid-April, a South Korean minister said on Tuesday as speculation swirled over Kim’s whereabouts and health.

Under Kim Jong -un, North Korea has expanded its arsenal of nuclear weapons and long-range ballistic missiles, and with no obvious successor, any change in leadership in the authoritarian country would raise concerns about instability that could impact other North Asian countries and the US.

The speculation about Kim’s health erupted after his unprecedented absence from ceremonies marking the April 15 birth anniversary of his grandfather and founder of the country, Kim Il Sung. South Korea’s unification minister Kim Yeon-chul, who oversees engagement with the North, said it was plausible that Kim decided against attending because of the coronavirus, given the stringent steps his government has taken to head off an outbreak.

“It is true that he had never missed the anniversary for Kim Il Sung’s birthday since he took power, but many anniversary events including celebrations and a banquet had been cancelled because of coronavirus concerns,” the unification minister told a parliamentary hearing.

'I don’t think that’s particularly unusual given the current (coronavirus) situation,” the minister said, though North Korea has said it has no confirmed cases of the coronavirus.

The South Korean minister noted that there were at least two instances since mid-January when Kim Jon-un had been unsighted for nearly 20 days.

The last time official media in the secretive North Korean state reported on Kim's whereabouts was when he presided over a meeting on April 11, but there have been near-daily reports of him sending letters and diplomatic messages.

South Korean officials emphasise they have detected no unusual movements in North Korea and have cautioned against reports that Kim may be ill.

The unification minister described reports that Kim had undergone a heart procedure, and that a Chinese medical team had travelled to North Korea, as “fake news”.

Citing three people familiar with the situation, Reuters reported on Saturday that China had dispatched a team to North Korea including medical experts to advise on Kim Jong-un, though it was unclear what the trip signalled in terms of Kim's health.

North Korea had cancelled some large events, and imposed a border lockdown and quarantine measures in an effort to prevent an outbreak of the coronavirus. But if Kim is hiding out due to fears surrounding Covid -19, it would“puncture a hole in the state media narrative of how this crisis has been perfectly managed”, said Chad O’Carroll, CEO of Korea Risk Group, which monitors North Korea.

“If he is merely trying to avoid infection, it should theoretically be very easy to release photos or videos.”