SEOUL (REUTERS) - South Korea reported more than 300 new coronavirus cases for a fifth straight day on Sunday (Nov 22), as officials warned that stricter rules could be imposed if the trend continues to threaten the highly populated capital of Seoul and surrounding areas.

The Korea Disease Control and Prevention Agency reported 330 new daily coronavirus cases as at midnight on Saturday, a drop from 386 reported the day before, a level not seen since August.

Officials warned that unless the number of infections drops substantially, they may raise the level of social distancing regulations.

Prime Minister Chung Sye-kyun said the government is mulling tougher distancing regulations for the greater Seoul area and the southwestern region, Yonhap news agency reported on Sunday.

"We're at a critical juncture of facing a large number of infections nationwide, as multiple new coronavirus cases have been reported simultaneously across the country," Mr Chung said.

"The government will discuss today pre-emptively raising the distancing rules to Level 2 in the greater Seoul area and to Level 1.5 in the southwestern Jeolla provinces, not waiting until the number of new cases increases enough to fulfill the requirements to adjust the level."

Level 2 is the third highest level of the country's five-tier Covid-19 alert system.

Under Level 2, restaurants must shut after 9pm (delivery and takeout are allowed after that), cafes can only have delivery and takeout, and karaoke rooms must close after 9pm. Additionally, meetings and events with more than 100 people are banned, companies are required to increase further the ratio of staff working from home, and schools can only run on one-third capacity.

Last week, South Korea tightened prevention guidelines ahead of highly competitive annual college entrance exams scheduled for Dec 3, and Prime Minister Chung called for all social gatherings to be cancelled.

Bars, nightclubs, religious services and sports events continue to be permitted with attendance restrictions, but that could change if officials impose more social distancing measures.

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.