A medical worker takes a break in front of an air cooler at a COVID-19 testing station in Gwangju, 268 kilometers south of Seoul, amid a heat wave on Friday, in this photo provided by a local ward office. (Yonhap)

South Korea's new COVID-19 cases fell below 80,000 for the first time in about a week, but the number of seriously ill patients hit a two-month high amid a virus wave driven by a highly contagious omicron subvariant, according to the nation's health authorities Sunday.

The country added 73,589 new COVID-19 infections, including 341 from overseas, bringing the total caseload to 19,776,050, the Korea Disease Control and Prevention Agency (KDCA) said.

Sunday's figure is down from the previous day's 82,002 due mainly to fewer tests on the weekend, with the daily count falling constantly since Wednesday.

But it is still larger than the 65,373 new cases logged a week earlier, as the country has seen a resurgence of the virus, triggered by the omicron subvariant BA.5.

The growth in new infections led to the surge in the number of seriously ill patients.

The country reported 284 critical cases Sunday, up from 242 a day earlier. It marked the highest figure since May 18 when the tally stood at 313.

The KDCA reported 20 deaths from COVID-19, raising the death toll to 25,047. (Yonhap)