A South Korean official who went missing from a fisheries patrol boat earlier this week was shot dead by North Korean troops who later burned his body, South Korea's military said Thursday.

The military did not explain how the official ended up in North Korean waters, but the Yonhap news agency cited unnamed intelligence sources in Seoul who said he had been attempting to defect to the North.

"Our military strongly condemns such an atrocity, and strongly demands North Korea provide explanations and punish those who are responsible," said General Ahn Young-ho, who is in charge of operations at the Joint Chiefs of Staff, at a briefing.