South Korean prosecutors have arrested a former defense minister and a former coast guard chief over the death of a fisheries official in waters near the de facto inter-Korean maritime border two years ago.

A crew member of a South Korean fisheries ministry boat was fatally shot by North Korea's military in September 2020 in the Yellow Sea, west of the Korean Peninsula.

South Korean coast guard officials initially said the crew member was trying to defect to the North. But they retracted the comment in June this year, telling reporters that there was no evidence to suggest such motives.

Prosecutors arrested former Defense Minister Suh Wook and former Coast Guard Commissioner General Kim Hong-hee on Saturday over their alleged involvement in covering up the facts and suspected abuse of power.

The arrests came as the government of President Yoon Suk-yeol expands an investigation into the 2020 killing of the crew member. There is speculation that the previous administration led by Moon Jae-in sought to cover up the incident to avoid a deterioration of ties with the North.

South Korean media say other top security officials of the previous administration, including former National Security Adviser Suh Hoon and former National Intelligence Service chief Park Jie-won, may also face charges.