South Korea has reported 386 new cases of the coronavirus in a resurgence that could force authorities to reimpose stronger social distancing restrictions after easing them in October to spur a faltering economy.
New cases topped 300 for the fourth day in a row after Tuesday saw the highest since August.
The figures released by the Korea Disease Control and Prevention Agency on Saturday brought the national caseload to 30,403, including 503 deaths.
More than 270 of the new cases come from the Seoul metropolitan area, where health workers have struggled to track transmissions in schools, private tutoring academies and religious facilities.
Infections were also reported in other major cities including Busan, Daejeon, Gwangju and Asan.
South Korea has so far managed to weather its COVID-19 epidemic without major lockdowns, relying instead on an aggressive test-and-quarantine campaign and mask-wearing.
Officials eased distancing measures to the lowest level in October, which allowed high-risk venues such as nightclubs and karaoke bars to reopen and fans to return to professional sports.
But the Korean Society of Infectious Diseases said on Friday the country could be reporting more than 1000 new infections a day in a week or two if social distancing measures are not strengthened.