In this Dec. 22, 2010, file photo, a government ship sails past the South Korean Navy's floating base as the sun rises near Yeonpyeong island, South Korea. AP

A South Korean fisheries official who went missing on Monday may have been shot dead by North Korean troops and later cremated after attempting to defect to the North, Yonhap news agency reported, citing unnamed intelligence sources in Seoul.

The official was reported missing from a South Korean fisheries patrol boat when it was about 10 kilometres (6 miles) south of the Northern Limit Line (NLL), a disputed line of military control that acts as the de facto maritime boundary between North and South Korea.

The exact reason the 47-year-old official was shot is still unknown, but North Korean troops may have been acting under anti-coronavirus orders, Yonhap quoted multiple sources as saying.

South Korea's defense ministry and National Intelligence Service did not immediately respond to requests for comment.