A South Korean aerial tanker carrying members of the virus-hit Cheonghae unit departed Africa on Monday to bring the troops home from an overseas anti-piracy mission, the defense ministry said, after 247 of them tested positive for the new coronavirus in the worst-ever mass infection among service members.

The military sent two KC-330 multirole aerial tankers to Africa the previous day to bring back all the members of the 301-strong unit under an operation codenamed "Mission Oasis," after 82 percent of them were found to be infected with COVID-19.

One of the aircraft departed a local airport at 7:25 p.m. (Seoul time), with the other to follow suit. They are expected to arrive home Tuesday.

After the first six COVID-19 cases were reported last week, virus tests on all of its members found that a total of 247 have contracted the virus.

"Test results on all 301 crewmembers of the unit showed that 247 tested positive and 50 negative. The samples of four individuals were undecipherable," the JCS said in a release.

As of Monday morning, 16 were at local hospitals for treatment, and the remainder were in isolation on their destroyer, Munmu the Great. (Yonhap)