It brought to 184 the total number of people diagnosed with MERS in the largest outbreak outside Saudi Arabia.
The latest cases involved two nurses from Seoul's Samsung Medical Center, the health ministry said.
The hospital, which has so far accounted for almost half of all confirmed cases, declared a 10-day suspension of most health services last month to stem the spread of the virus.
As the hospital continued to report new cases, the shutdown was extended indefinitely.
