South Korea is preparing to send aerial tankers to Africa to bring home all members of a naval unit on an anti-piracy mission amid fears of a mass COVID-19 infection on their destroyer following recent confirmed cases, officials said Friday.

On Thursday, the defense ministry said six service members of the 34th contingent of the Cheonghae Unit aboard the Munmu the Great tested positive for the new coronavirus and around 80 out of about 300 personnel showed symptoms consistent with the virus.

"We are considering bringing home all the members by sending aerial tankers so as to take necessary measures in a swift manner," a defense ministry official said.

In a message sent to families of the crew members, the head of the unit said all the crew members are expected to be airlifted home sometime next week.

The military is also considering sending a team of troops to pilot the Munmu the Great home after all Cheonghae Unit members have been sent home. The current contingent had originally been scheduled to return home in August, with a replacement group taking over the mission.

President Moon Jae-in on Thursday ordered the mobilization of aerial tankers to provide swift medical support to the infected people and to bring them back home if they cannot receive necessary treatment.

South Korea operates four Cygnus multi-role tankers aimed at expanding its operational areas. Each can carry 47 tons of cargo and 300 crewmembers, according to the ministry.

Contact tracing is under way, but the infections appeared to have begun after the vessel was docked at a nearby port late last month to load supplies, according to the officials.

Fears of a mass infection have grown as the service members have been kept in close proximity to each other while staying together for months aboard the ship.

None of them have been vaccinated, as they left South Korea in February just before the country began its inoculation campaign.

"Around 80 people showing symptoms are under treatment. Five of them were taken to hospitals, and the remaining members with mild symptoms have been in isolation on the vessel," a Joint Chiefs of Staff (JCS) official said.

"We provided them with additional medical supplies and are closely monitoring the situation," he said.

All the unit members underwent virus tests, and the results are expected to be available later in the day at the earliest, he added.

So far, around 73 percent of around 1,300 troops on overseas missions have been fully vaccinated, including the 35th batch of the Cheonghae Unit, which left the country in June as a replacement. (Yonhap)