North Korea has suggested its Covid-19 outbreak began when balloons were flown in from South Korea.
Activists for years have flown balloons across the border to distribute hundreds of thousands of propaganda leaflets critical of North Korean leader Kim Jong-un.
North Koreans have been ordered to “vigilantly deal with alien things coming by wind and other climate phenomena, and balloons in the areas along the demarcation line and borders”, the official KCNA news agency said.
South Korea’s Unification Ministry said there was no chance South Korean balloons might have spread the virus to North Korea.
Coronavirus is spread by people in close contact who inhale airborne droplets, more likely in enclosed, poorly ventilated spaces, say world health authorities.
Ties between North and South Korea remain strained amid a long-running stalemate in US-led diplomacy on persuading North Korea to abandon its nuclear ambitions in return for economic and political benefits.
South Korean and US officials have recently said North Korea is ready for its first nuclear test in five years amid its torrid run of weapons tests this year.
A state media report said North Korea’s epidemic prevention centre had found infection clusters in the town of Ipho near its south-eastern border with South Korea and that some Ipho residents with feverish symptoms travelled to Pyongyang.
The centre said an 18-year-old soldier and a five-year-old had contact with “alien things” in the town in early April and later tested positive for the Omicron coronavirus variant.
It said anyone finding “alien things” must notify authorities immediately so they could be removed.
Leaflet campaigns were largely halted after South Korea’s previous liberal government passed a law making them a criminal offence, and there were no public balloon attempts made in early April.
An activist who is standing trial for past activities flew balloons carrying propaganda leaflets across the border in late April after halting them for a year.
Park Sang-hak floated balloons twice in June, switching the cargo on those attempts to Covid-19 relief items such as masks and painkillers.
Police are still investigating the recent leafleting activities by the activist, Cha Duck-chul from the South’s Unification Ministry told reporters on Friday.