The Korea Disease Control and Prevention Agency (KDCA) posted 7,850 cases for Tuesday, with the number of patients in serious condition also reaching a fresh high at 964.
Total infections in the pandemic so far have risen to 536,495, including 128 cases of the potentially more transmissible Omicron variant, with 4,456 deaths, according to the KDCA.
Prime Minister Kim Boo-kyum said the government is considering reimposing strict distancing curbs including a ban on gatherings and a curfew on dining in eating establishments. An official announcement is expected on Friday.
"We're looking at the current situation very seriously, and seeking to implement even stronger social distancing measures," Kim told an intra-agency meeting, without elaborating.
South Korea has fully vaccinated more than 94 percent of its adults so far, and is accelerating its ongoing campaign promoting booster shots by shortening intervals for all ages.
But the number of new cases has surged almost five times and serious cases tripled since distancing rules were eased last month under a 'living with Covid-19' policy.
The daily death toll also hit its highest levels at 94 on Monday, compared with around 10 in early November, KDCA data showed.
Authorities have scrapped plans for further relaxing, but remained hesitant to trigger a circuit breaker it had vowed to issue if more than 75 percent of intensive care unit (ICU) beds are used nationwide, due to business backlash and growing public fatigue.
More than 81 percent of ICU beds are occupied nationwide and the ratio topped 86 percent for the greater Seoul area as of Wednesday.