Two American service members and a South Korean national working for the US Forces Korea (USFK) have tested positive for the new coronavirus, the US military said Thursday.

A soldier at Camp Casey in the northern city of Dongducheon was confirmed to have contracted COVID-19 on Wednesday after developing symptoms, according to USFK.

Dongducheon, 40 kilometers north of Seoul, is where more than 100 infections have been reported among some 4,000 foreigners living in the city.

Following a spike in virus cases, USFK restricted its members from off-post dining in Dongducheon, and banned travel to and from the city and Camp Casey except for approved mission essential activities.

Separately, another soldier and a Korean national contractor at Camp Humphreys in Pyeongtaek, 70 km south of Seoul, tested positive for the virus Tuesday.

The service member was found infected through the US military's surveillance testing program, while the contractor tested positive after developing symptoms. The civilian employee last visited the base Saturday.

"KDCA and USFK health professionals are actively conducting contact tracing to determine whether anyone else may have been exposed to these individuals, and to identify and ensure all known on-post and off-post facilities visited by the individuals are thoroughly cleaned," the US military said in a release. KDCA stands for the Korea Disease Control and Prevention Agency.

The latest cases raised the total number of infections reported among the USFK population to 759. (Yonhap)