North Korean leader Kim Jong Un has placed one city in lockdown over fears the country has its first coronavirus case.
He believed "the vicious virus" may have entered the country after a resident in Kaesong, on the border with South Korea , displayed suspected COVID-19 symptoms, North Korea's Central News Agency reported.
The lockdown was declared on Friday afternoon and, if it is confirmed, a positive test result would be the North's first official coronavirus case since the start of the global pandemic.
North Korea has repeatedly said it has no virus cases on its territory, a claim that has been questioned by foreign experts.
KCNA reported that the individual with suspected COVID-19 was a runaway who had fled to South Korea years ago before illegally crossing the border into the North early last week.
The news agency said the person's respiratory secretion and blood tests showed they were "suspected to have been infected" with the virus.
Mr Kim said there was a "a critical situation in which the vicious virus could be said to have entered the country".
He said he took "the preemptive measure of totally blocking Kaesong City and isolating each district and region from the other within 24 July afternoon just after receiving the report on it," according to KCNA.
The suspected case and others who were in contact, as well as those who have been to Kaesong in the last five days, were reportedly placed under quarantine.
The North has described its anti-virus efforts as a "matter of national existence".
Earlier this year, the country shut down nearly all cross-border traffic, banned foreign tourists and mobilised health workers to quarantine anyone with symptoms.
Mr Kim previously urged officials to stay alert over the coronavirus threat and warned that complacency risks "unimaginable and irretrievable crisis".
Foreign experts have said a coronavirus outbreak in North Korea could cause dire consequences due to its poor public health care infrastructure and lack of medical supplies.
Kaesong has an estimated population of 200,000 and is located just north of the land border with South Korea.
Last month, North Korea blew up an inter-Korean liaison office in Kaesong in protest at a campaign by South Korea activists who have been sending anti-Pyongyang leaflets across the border.
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The South Korean government has not yet commented on the North Korean announcement.
Leif-Eric Easley, a professor at Ewha University in Seoul, said: "Blaming an alleged return defector for bringing COVID-19 into the country is likely intended to shift blame for spread of the virus away from China and Pyongyang and on to Seoul.
"This may also be a tactic for ratcheting up diplomatic pressure on (South Korea) and trying to further dissuade North Koreans from defecting to the South."