South Korea's daily new coronavirus cases rose back to above 600 on Saturday, health authorities said, as the fourth wave of the virus continued with sporadic cluster infections and variant cases.

The country reported 666 more COVID-19 cases, including 633 local infections, raising the total caseload to 135,344, the Korea Disease Control and Prevention Agency said.

Saturday's daily caseload compares with 561 on Friday, 646 on Thursday and 554 on Wednesday.

There were four additional virus deaths, raising the total to 1,926.

Currently, the greater Seoul area, home to more than half of the country's 52 million people, is under Level 2 social distancing, the third highest in the five-tier scheme, while the rest of the country is mostly subject to Level 1.5 distancing. Gatherings of five or more people are banned nationwide in principle.

On Friday, South Korea said it will extend the current distancing rules for another three weeks starting Monday, as the number of new daily average patients has not been budging below the 500 mark with more people enjoying warm weather activities.

The country has reported more than 1,000 cases of variant strains of COVID-19 from Britain, South Africa, Brazil and India, with southern cities, such as Ulsan, reporting the most variant cases.

While the country launched its vaccination program on Feb. 26, it has been sluggish in inoculating South Koreans amid the tight supply of vaccines.

As of Friday, 1.7 million people, or 3.3 percent of the country's population, have been fully vaccinated, receiving both doses of two-part vaccines.

A total of 3.79 million people, or 7.4 percent, have received their first shots, up 13,764 from a day earlier.

AstraZeneca's vaccine has been given to 2.06 million people, while 1.73 million have received that of Pfizer.

Under the country's vaccination blueprint, South Korea aims to inoculate 13 million people by the end of June and achieve herd immunity by November.

Of the locally transmitted cases, 205 came from Seoul, and the surrounding Gyeonggi Province accounted for 163.

The total number of people released from quarantine after making full recoveries was 874, up 125,032 from a day earlier. (Yonhap)