South Korea confirmed 376 more coronavirus cases on Sunday, taking the national total to 3,526 infections, the largest in the world outside China.
Nearly 90% of the new cases were in Daegu, the centre of the country's outbreak, and its neighbouring North Gyeongsang province, the Korea Centers for Disease Control and Prevention said in a statement.
The national total is expected to rise further as authorities screen more than 260,000 members of the Shincheonji Church of Jesus, a secretive entity often accused of being a cult that is linked to around half of the country's cases.
The streets of Daegu -- South Korea's fourth-largest city with a population of 2.5 million -- have been largely deserted for days, apart from long queues at the few shops with masks for sale.
Authorities have urged the public to exercise caution and anyone with a fever or respiratory symptoms to stay home.
But officials say they are not considering a citywide quarantine for the city in the manner of the lockdown imposed on the central Chinese city of Wuhan, where the virus first emerged.
The government has imposed a one-week extension on school breaks nationwide. In Daegu, the school break has been extended by three weeks.