South Korea's daily new coronavirus cases rose back above 500 on Tuesday, with health authorities remaining on alert over a potential spike amid spreading variant cases.

The country reported 511 more COVID-19 cases, including 483 local infections, raising the total caseload to 128,283, the Korea Disease Control and Prevention Agency (KDCA) said.

Tuesday's figure rebounded from 463 a day earlier but is lower than 564 Sunday and 701 Saturday. The daily caseload usually spikes after weekends as more people get tested.

There was four additional deaths from the virus, raising the total to 1,879. The fatality rate was 1.46 percent.

Later in the day, health authorities and local governments reported 467 new virus cases as of 6 p.m., up 96 cases from the same time on Monday.

Daily infections have shown no signs of slowing down in the past week as people have increased their gatherings and activities amid the warmer weather.

Spreading variant cases are putting health authorities on edge as the country's southeastern region and cities are reporting a spike in mutated cases.

The country is revving up its vaccination drive with an aim to inoculate 13 million people by June and 36 million by September. It aims to achieve herd immunity by November.

The country will receive 14.2 million doses of vaccines in May and June, enough to vaccinate up to 13 million people by end-June, according to the KDCA.

The health agency said 7.23 million doses of AstraZeneca's vaccine will arrive in the country between May 14 and the first week of June, while 5 million doses of Pfizer's vaccine will also be supplied by June.

A total of 3,692,566 people have received their first shots of COVID-19 vaccines, accounting for 7.2 percent of the country's population, since the country started its vaccination program on Feb. 26.

AstraZeneca's vaccine has been administered to 2,025,401 people, while 1,667,165 have received Pfizer's vaccine.

Health authorities said around 8.95 million people aged between 60 and 74 will receive vaccination shots in the coming weeks.

Starting May 27, people between age 65 and 74 will be administered with AstraZeneca's vaccine. Those between age 60 and 65 will receive AstraZeneca's vaccine beginning June 7.

Of the new locally transmitted cases, 310 cases came from the capital area, with 163 from Seoul, 127 from Gyeonggi Province and 20 from Incheon, just west of Seoul.

South Korea's southeastern port city of Busan reported 13 more cases.

There were 28 additional imported cases, bringing the country's total number of imported cases to 8,608.

The number of seriously or critically ill COVID-19 patients was 171, up 10 from the previous day.

The total number of people released from quarantine after making full recoveries was 118,717, up 873 from a day earlier, with 7,687 people being isolated for COVID-19 treatment. (Yonhap)