South Korea's daily coronavirus cases bounced back to above 4,000 for the first time in six days Wednesday, putting health authorities on high alert over a possible resurgence amid omicron concerns.

The country added 4,388 new COVID-19 infections, including 4,007 local infections, raising the total caseload to 674,868, according to the Korea Disease Control and Prevention Agency (KDCA).

Wednesday's figure was up 1,291 from a day earlier and 53 down from last Wednesday.

The country reported 52 more COVID-19 deaths, raising the death toll to 6,166, according to the health authorities. The fatality rate came to 0.91 percent.

The number of critically ill COVID-19 patients stood at 749, staying below 800 for the fourth straight day.

The government has reimposed toughened antivirus restrictions since mid-December after daily infections soared to nearly 8,000 under the eased "living with COVID-19" scheme.

The current antivirus curbs, set to be in effect until Sunday, include a four-person cap on private gatherings across the nation and a 9 p.m. business hour curfew on cafes and restaurants.

As the daily caseload has dropped in recent weeks, the government is reviewing whether to relax social distancing rules again from next week to help ease the burden on citizens and small businesses.

The government is set to hold a session later in the day to assess the risk level of the pandemic and decide on possible revisions to the current social distancing rules.

As of Wednesday, 43.22 million people, or 84.2 percent of the country's 52 million population, have been fully vaccinated, and 21.81 million, or 42.5 percent, have received booster shots, the health authorities said.

The number of cases from overseas came to an all-time high of 381, raising the total caseload to 19,800. (Yonhap)