South Korea's daily coronavirus cases stayed below 4,000 for the third straight day Sunday as the country maintained tightened distancing curbs amid concerns over the spread of the omicron virus variant.

The country added 3,376 new COVID-19 infections, including 3,140 local infections, raising the total caseload to 664,391, according to the Korea Disease Control and Prevention Agency (KDCA).

The daily caseload fell from 3,510 the previous day and 3,716 on Friday.

South Korea reported 51 more COVID-19 deaths, raising the death toll to 6,037, the KDCA added. The fatality rate was 0.91 percent.

The number of critically ill COVID-19 patients stood at 821, staying below 1,000 for six consecutive days.

In early November, the government eased antivirus restrictions as part of efforts to return to normalcy in phases under the "living with COVID-19" scheme.

Daily cases, however, soared to a record high of 7,848 on Dec. 15, prompting the government to reimpose a set of revised virus restrictions until Jan. 2 and later extend them until Jan. 16.

The restrictions include a four-person cap on private gatherings across the nation and a 9 p.m. business hour curfew on cafes and restaurants.

South Korea plans to bring in antiviral COVID-19 treatment pills this week, vowing to make sure they are used as swiftly as possible.

The KDCA said 43.03 million people, or 83.8 percent of the country's 52 million population, have been fully vaccinated, and 21 million, or 41 percent, have received booster shots.

The number of cases from overseas came to 236, raising the total caseload to 18,903.

Of the locally transmitted cases, Seoul reported 891, while 1,081 came from the surrounding Gyeonggi Province and 172 from Incheon, a port city west of the capital city. (Yonhap)