Seven American civilians working at US Forces Korea (USFK)'s Yongsan garrison in central Seoul have tested positive for the new coronavirus, the US military said Thursday.

One US Department of Defense (DoD) employee and four contractors, who work together on the base, have been in isolation after coming into direct contact with their colleague who earlier tested positive for COVID-19, according to the USFK.

The sixth case is the spouse of one of the contractors, who works at a separate location inside the base, the USFK said.

The seventh is a civilian DoD worker who does not have a direct relationship with the other six patients, according to the US military.

All seven people are currently in isolation at their off-installation residences while awaiting transportation to a medical facility in Camp Humphreys in Pyeongtaek, some 70 kilometers south of Seoul, it added.

"KDCA and USFK health professionals are actively conducting contact tracing to determine whether anyone else may have been exposed, and to identify and ensure all known on-post and off-post facilities visited by the individuals are thoroughly cleaned," USFK said in a statement.

USFK banned "all leisure travel" to the Yongsan garrison from Tuesday through Saturday for contact tracing and other necessary antivirus measures.

The latest cases raised the total number of infections among USFK-affiliated individuals to 590, most of whom tested positive upon arrival in South Korea from the US. (Yonhap)