South Korea's new coronavirus cases stayed below 6,000 for the second straight day Sunday following fewer tests on Christmas Day but critical cases remained high.

The country added 5,419 more COVID-19 cases, including 5,339 local infections, bringing the cumulative total to 607,463, the Korea Disease Control and Prevention Agency (KDCA) said.

Sunday's tally fell from 5,842 cases on Saturday, 6,233 on Friday and 6,917 on Thursday, apparently helped by antivirus restrictions.

The number of critically ill patients slightly fell to 1,081 from a record high of 1,105 a day earlier, the KDCA said.

The country added 69 more deaths from COVID-19, bringing the total to 5,245. The fatality rate stood at 0.86 percent.

The country also reported 33 new omicron variant cases, bringing the total to 376, 161 of which are imported and 215 locally transmitted, the KDCA said.

Of the 33 newly confirmed cases, 23 came from overseas. As for the 10 locally transmitted ones, health authorities have yet to find out the exact course of the infection.

Health authorities have been urging people to get booster shots, especially senior citizens, to better protect themselves from COVID-19.

As of Sunday, 85.6 percent of the country's 52 million people had received their first shots of COVID-19 vaccines, and 82.4 percent had been fully vaccinated, while 29.6 percent had gotten booster shots, the health agency said.

The country has been enforcing stricter virus restrictions since last weekend, to stem the spread of the virus variant.

Under the measures, which will remain in effect until Jan. 2, the maximum size of private gatherings is limited to four people nationwide, from the previous limit of six in the capital area and eight elsewhere.

A 9 p.m. or 10 p.m. curfew is applied to businesses, depending on their type of service.

The authorities are also focusing on securing hospital beds as the number of critically-ill virus patients stayed above 1,000 for the sixth straight day through Sunday.

Of the locally transmitted cases confirmed Sunday, Seoul reported 1,889 cases and Gyeonggi Province that surrounds the capital logged 1,634 cases. Incheon, just west of Seoul, registered 325.

There were 80 cases from overseas, raising the total imported cases to 16,825. (Yonhap)