Nearly 90 percent of some 300 service members in the anti-piracy Cheonghae Unit stationed in African waters have tested positive for COVID-19.
The sailors returned home on Tuesday via military aircraft after 247 of them, or 82 percent of the unit, tested positive for the virus.
The Defense Ministry said on Wednesday that the government re-tested all 301 members the previous day and 266, or 88 percent of the unit, tested positive. The ministry said 23 tested negative, while 12 others are awaiting another round of tests.
The confirmed patients will receive treatment at hospitals or facilities where they are currently staying.
Those who tested negative will be transported to a naval facility in Jinhae in South Gyeongsang Province for isolation for an unspecified period.