SEOUL (Reuters) -- North Korean troops shot dead a South Korean fisheries official who went missing earlier this week, before dousing his body in oil and setting it on fire in what was likely an effort to prevent a coronavirus outbreak, South Korea's military said on Thursday.
South Korea's military said evidence suggested the man was attempting to defect to the North when he was reported missing from a fisheries boat on Monday about 10 km (6 miles) south of the Northern Limit Line (NLL), a disputed demarcation of military control that acts as the de facto maritime boundary between the two Koreas.
Why the 47-year-old official was shot was not known but North Korean troops appear to have been acting under anti-coronavirus orders, South Korea's military said.
The presidential Blue House's national security office said the killing was a "crime against humanity", and called on North Korea to apologise and put measures in place to prevent a recurrence of similar incidents in the future.
Citing intelligence sources, the military said the unidentified man appeared to have been questioned at sea, north of the NLL and about 38 km (24 miles) from where he went missing, before he was executed on an "order from a superior authority". Troops in gas masks then doused the body in oil and set it on fire.
South Korean President Moon Jae-in said the North's shooting of a South Korean civilian was "shocking" and "unpardonable", Yonhap news agency said, citing a presidential Blue House spokesman.
Moon also ordered the South Korean military to tighten their alert to protect the lives of citizens.
The military said it sent a message on Wednesday to the North through the land border demanding explanations, but has not received any response yet.
"Our military strongly condemns such an atrocity, and strongly demands North Korea provide explanations and punish those who are responsible," General Ahn Young-ho, who is in charge of operations at the Joint Chiefs of Staff, told a briefing.
The U.S. military commander in South Korea said this month that North Korean troops had been given "shoot-to-kill orders" to prevent the coronavirus entering the country.
Such strict enforcement of those orders may be an attempt to prevent an outbreak from disrupting a major military parade expected to be held on Oct. 10 when the country commemorates the founding of the ruling Workers' Party of Korea, said Chad O'Carroll, CEO of Korea Risk Group, which monitors North Korea.
"In many ways, this parade is a huge potential viral risk," he said in a post on Twitter. "And it seems paranoia about that risk is at play (with) shoot-to-kill rules."
In July, a man who had defected to South Korea three years ago triggered a coronavirus scare when he crossed back over the heavily monitored border into North Korea, which says it has had no cases of the disease.
His arrival prompted North Korean officials to lock down a border city and quarantine thousands of people over fears he may have had the coronavirus, though the World Health Organization later said his test results were inconclusive.
Last week, South Korean police arrested a defector who they said had tried to return to North Korea by breaking into a military training site in South Korea's border town of Cheorwon.