Analysts initially said Pyongyang's disclosure of the Covid cases at this time was significant and could hamper the state's nuclear ambitions, which have been on show this year.

But hours after the Covid announcement on Thursday, North Korea fired three short-range ballistic missiles towards the Sea of Japan, South Korea's joint chiefs of staff said.

North Korea has claimed to have conducted more than a dozen banned missile tests, including one of an intercontinental ballistic missile, a weapon it hadn't tested in more than four years.

Yang Moo-jin, a professor at the University of North Korean Studies, told AFP that North Korea might shelve plans for a nuclear test to focus on battling the outbreak, though if public fears escalated, Mr Kim may go ahead with a test "to divert this fear to another place".

But Leif-Eric Easley, a professor at Ewha University, said that North Koreans "may be less interested in nuclear or missile tests when the urgent threat involves coronavirus rather than a foreign military".

He added that he believed Pyongyang would "likely double down" on its lockdowns, given that it was entering a "period of uncertainty in managing its domestic challenges and international isolation".

Despite North Korea's claims that it had "shining success" in keeping out Covid, there have been signs throughout the pandemic of the virus' potential presence in the country. There were several unconfirmed reports of Covid cases previously.

In June last year, state media reported that Mr Kim had punished officials over a "grave incident" related to Covid, but did not specify details.

Then in September, the state held a military parade featuring lines of soldiers wearing hazmat suits and masks, which some analysts saw as a sign that a special force was created to help prevent the spread of Covid.

North Korea shares land borders with South Korea and China, which have battled outbreaks. China is now struggling to contain an Omicron wave with lockdowns in its biggest cities.