SEOUL, South Korea (AP) — North Korea is further toughening restrictions on entering seawaters as part of elevated steps to fight the coronavirus pandemic, state media said Sunday, two days after South Korea said the North had banned sea fishing.

The Korean Central News Agency reported the country is mobilizing more anti-virus units and establishing strong steps to “completely remove uncivilized and unhygienic elements that could help make room for the spread of an epidemic” at winter. Some experts say the coronavirus can spread more broadly during cold weather when people typically spend more time indoors.

KCNA said officials were building firm anti-epidemic measures along border areas to prevent the coronavirus from entering the country. In front-line coastal areas, authorities were working out more stringent rules for venturing out at sea and collecting filthy materials in the waters, according to KCNA.

North Korea has maintained no single virus case has been found on its territory, a claim widely questioned by outside experts. Despite its claim, North Korea has swiftly sealed its borders, flew out diplomats and isolated residents with symptoms. A major outbreak in North Korea could have devastating consequences because of its broken health care system and a chronic lack of medicines.

North Korea has previously mentioned a restriction on entering the sea. Sunday's report came after South Korea's spy service told lawmakers Friday that the North’s anti-virus steps included a ban on fishing and salt production, as well as and the lockdown of the capital, Pyongyang, northern Jagang province and other areas.

Lawmakers who attended Friday's closed-door briefing also cited the National Intelligence Service as saying that North Korea executed an official for breaching regulations restricting the import of goods in August and a money changer for a falling exchange in October,

Ha Tae-keung, one of the lawmakers, quoted the agency as saying North Korean leader Kim Jong Un is displaying “excessive anger” and taking “irrational measures” over the pandemic and its economic impact.

In September, South Korea accused North Korea of fatally shooting a South Korean fishery official found in the North’s waters before burning his body apparently in line with an anti-virus policy that involves shooting anyone illegally crossing the border. North Korea later acknowledged and apologized for the killing, but claimed it only burnt his floating device, not his body.