Six crew members aboard a South Korean naval destroyer serving an anti-piracy mission overseas have been diagnosed with COVID-19, raising concerns about a possible cluster within the vessel. 

The Joint Chiefs of Staff(JCS) said on Thursday that an officer on the four-thousand-400-ton naval destroyer Munmu the Great operated by South Korea's anti-piracy Cheonghae Unit displayed pneumonia-like symptoms on Wednesday. 

Six people who came into contact with the officer were tested and all tested positive, the JCS said. The officer was taken to a local hospital and is also scheduled to be tested. 

The Cheonghae Unit has put the infected crew into quarantine within an isolated facility on the destroyer while some crew members who showed similar symptoms were also placed in cohort quarantine. All 300 or so soldiers in the unit will undergo a polymerase chain reaction(PCR) test. 

The 34th contingent of the unit left South Korea in February and all its members have yet to be vaccinated.