Seoul: South Korea's military has recorded its biggest cluster of coronavirus infections to date, with more than 80% of personnel aboard a destroyer on anti-piracy patrol in the Gulf of Aden testing positive.

The surge comes as the country battles its worst-ever outbreak of Covid-19 cases at home, with another 1,252 new infections reported on Sunday. While, 247 cases are not directly linked to new domestic infections, with the destroyer having left South Korea to start its mission in February.

The country's Joint Chiefs of Staff Monday stated that just 50 of the ship's complement of 301 personnel have tested negative in an outbreak first reported on July 15.

However, the authorities have begun an operation to airlift them home, while a replacement team will steer the vessel back home.

South Korea has recorded 179,203 cases and 2,058 deaths.

So far, 31.4% of its 52 million population has received at least one dose of vaccine, while 12.7% have been fully vaccinated.

Citing military sources, Yonhap news agency reported none of the affected personnel aboard the destroyer were classified as severe cases, though one person has developed conditions that require close observation.

In addition, authorities had decided vaccination at sea was not a viable option as it would limit monitoring for any allergic reaction such as anaphylaxis due to the nature of the operational mission.

The Korea Disease Control and Prevention Agency (KDCA) said in a statement, “The ship would not meet the cold-storage requirements for some vaccines, including Pfizer-BioNTech vaccines for soldiers aged under 30”

The country has excluded people aged below 30 from receiving AstraZeneca or Johnson & Johnson vaccines over concerns of rare but serious blood clots linked to the shots.