South Korea's daily new coronavirus cases stayed in the high 600s for the second straight day Saturday as health authorities warn that the country may be at the start of a fourth wave of infections.

The country reported 677 more COVID-19 cases, including 662 local infections, raising the total caseload to 108,945, the Korea Disease Control and Prevention Agency (KDCA) said.

The tally is slightly larger than 671 on Friday but marked a fall from a three-month high of 700 new cases Thursday.

The average daily caseload reached 601 in the last seven days on lingering cluster infections and untraceable cases.

The country added one more death from COVID-19, increasing the total to 1,765.

Despite worries over a bigger wave of the pandemic, South Korea on Friday decided to keep the current level of social distancing rules through May 2, though some of the measures for small businesses will be tightened.

The greater Seoul area, home to half of the nation's 51.7 million population, is under the Level 2 distancing scheme, the third highest in the five-phase system. The rest is under Level 1.5, but some municipalities have adopted Level 2 measures.

Private gatherings of five or more people are banned nationwide. A gathering ban on bars and other entertainment establishments, such as nightclubs, will go into effect Monday in Seoul, Incheon, Busan and Gyeonggi Province.

Of the newly confirmed locally transmitted cases, 63.3 percent, or 421 cases, came from the capital area, with 198 from Seoul, 199 from Gyeonggi Province and 24 from Incheon, 40 kilometers west of the capital. The southern port city of Busan, the country's second-largest city, reported 56 more cases.

There were 15 additional imported cases, down from 27 a day earlier. The country's total number of imported cases is now at 7,804.

The number of seriously or critically ill COVID-19 patients was 108, down five from the previous day.

The total number of people released from quarantine after making full recoveries was 99,301, up 515 from a day earlier, with 7,879 people being isolated for COVID-19 treatment, up 161 from a day ago.

South Korea has carried out 8,106,630 COVID-19 tests, including 47,517 from the previous day. (Yonhap)