A South Korean fisheries official who went missing this week was questioned in North Korean waters before being shot dead by troops who then doused his body in oil and set it on fire, South Korea’s military said.

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 10km 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...