Two former US service members and their spouses have tested positive for the new coronavirus after coming into contact with another retired couple who were earlier confirmed to have contracted the virus, US Forces Korea said Friday.

The four individuals tested positive Thursday following direct contact with the other couple who was confirmed to have been infected with the virus the previous day, according to the US military.

"Contact tracing revealed the six individuals had contact with each other on Dec. 25," it said.

One of the two couples newly confirmed with the virus last visited Camp Humphreys in Pyeongtaek, 70 kilometers south of Seoul, on Tuesday while the other was last on the base on Dec. 23.

The four of them -- all residing in the southeastern city of Sangju -- are currently in isolation at a facility in Camp Humphreys designated for coronavirus patients.

"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 contractors are thoroughly cleaned," it said. KDCA stands for the Korea Disease Control and Prevention Agency.

The latest cases raised the total number of infections among the USFK population to 486, most of whom tested positive upon their arrival in South Korea from the United States. (Yonhap)