A US citizen working at a US Forces Korea (USFK) base tested positive for the coronavirus on Monday, bringing the total number of USFK-related infections to 13, the military said.

The latest COVID-19 patient is an American contractor working at Camp Humphreys in Pyeongtaek, 70 kilometers south of Seoul, according to USFK.

He is currently in isolation at his off-base residence, and he last visited the garrison on Friday, it added.

"KCDC and USFK are actively conducting contact tracing to determine whether anyone else may have been exposed," USFK said in a release. KCDC is the acronym of the Korean Centers for Disease Control and Prevention.

Of the 13 confirmed cases, two are active-duty soldiers and the remainder are either USFK employees or family members of service members.

USFK remains at a level of "high" risk across the peninsula and is implementing various control measures to stop the spread of the virus, including a declared Public Health Emergency by its commander Gen. Robert Abrams last week to issue related guidance and enforce compliance, according to his office.

As the Pyeongtaek compound has seen a series of coronavirus infections in recent days, USFK brought its Health Protection Condition Levels (HPCON) a notch higher to "Charlie Plus," or "C+" for Camp Humphreys on Friday. All other installations are operating at HPCON-Charlie.

The C+ level calls for restricting all movement, except for mission essentials and basic needs, and shutting down several major facilities, such as schools, government offices and religious facilities, according to USFK. (Yonhap)