A woman enters a vaccine clinic in Seoul to get a booster shot for omicron subvariants of the coronavirus on Monday. (Yonhap)

South Korea's new coronavirus cases swelled to over 60,000 on Tuesday, with a possible winter surge of the virus on the horizon.

The country reported 62,273 new COVID-19 infections, including 52 from overseas, bringing the total to 25,919,183, the Korea Disease Control and Prevention Agency said.

The figure compared with 58,363 cases a week ago, 43,741 two weeks ago and 15,465 four weeks ago, showing a sustained increase in infections.

The average daily cases for the past seven days were 43,370.

The country added 30 deaths from COVID-19 on Tuesday, bringing the death toll to 29,420. The number of critically ill patients stood at 360, down five from a day earlier, the KDCA said.

Health authorities have warned that highly contagious omicron subvariants could trigger a virus resurgence in South Korea, with cases possibly peaking as high as 200,000 in the cold winter months. A possible outbreak of a "twindemic" of COVID-19 and seasonal influenza is also fueling concerns.

The government plans to announce a set of antivirus measures later this week, including ways to expand vaccine shots and oral medicines and to better protect vulnerable groups. It expanded booster shots against omicron subvariants to all adults aged over 18 the previous day. (Yonhap)