The Korea Disease Control and Prevention Agency reported 330 new daily coronavirus cases as of midnight on Saturday, a drop from 386 reported the day before, but the fifth straight day of more than 300 new cases.

"The third wave of COVID-19 outbreaks is increasingly in full swing," Health Minister Park Neung-hoo told a briefing. "The situation is extremely serious and grave."

A nationwide outbreak was being driven by clusters of infections in the densely-populated Seoul metropolitan area, he said, home to around half of the country's 52 million residents.

From Tuesday, major coffee shops in the Seoul area can only offer takeaway and delivery service, while restaurants must close to in-person dining after 9 pm. Other restrictions will be placed on facilities like gyms, with attendance caps on religious gatherings and sporting events.

Earlier in the day Prime Minister Chung Sye-kyun told a government meeting that preemptive distancing regulations might be needed to head off a wider outbreak, Yonhap news agency reported.

"We're at a critical juncture of facing a large number of infections nationwide," Chung said.

On Saturday, a KDCA official said the country could be facing an outbreak that surpasses two earlier waves of infections, if it fails to block the current spread.

The tightened prevention guidelines are aimed partly at allowing students to go ahead with highly competitive annual college entrance exams scheduled for December 3.

South Korea has employed an aggressive tracing, testing, and quarantine effort to stamp down outbreaks without imposing lockdowns. But the country has been dogged by a persistent number of small infections, bringing the total number of cases to 30,733 with 505 deaths.

Australian Associated Press