South Korea on Wednesday reported 2,080 COVID-19 cases, according to the Health Ministry, a sharp rise from 1,497 a day earlier.
The total number of cases in the country battling the fourth wave of coronavirus rose to 277,989, while the death toll has reached 2,380, with 13 new fatalities over the past day, the ministry said.
Meanwhile, the country's capital Seoul city recorded 804 cases over the past 24 hours, its highest daily figure since the start of the pandemic.
"Relaxed vigilance and increased population movement are pushing up the spread of the virus in the capital region," Yonhap News Agency quoted Sohn Young-rae, a senior health official, as saying.
The health authorities also worried over the new spike ahead of a major Chuseok holiday, set for Sept. 20-22.
Chuseok is one of the country's biggest traditional holidays, during which families hold rituals thanking their ancestors and visit their graves.
To contain the spread of the virus, authorities have already extended until Oct. 3 the current social distancing measures-Level 4 in the greater Seoul area, which is the highest in the four-tier system, and Level 3 in other regions.
So far, over 34 million people-67.3% of the country's population-have received their first vaccine dose, while 20.71 million people have gotten the second.