South Korea's daily new virus cases fell back to the 500s on Monday for the first time in five days on fewer tests over the weekend.

But health authorities have been keeping tabs on the trend of new virus infections amid concerns over a steady rise in cases of the highly contagious Delta variant and others ahead of the implementation of eased social distancing measures later this week,

The country reported 501 more COVID-19 cases, including 472 local infections, raising the total caseload to 155,572, the Korea Disease Control and Prevention Agency (KDCA) said. The latest figure was down 113 from the previous day.

The country added two more deaths, raising the death toll to 2,015. The fatality rate was 1.3 percent.

Daily caseloads soared to the 600s from the high 300s on Wednesday due to sporadic cluster infections across the country.

Along with the rise in the number of new virus infections, untraceable cases took up 25.3 percent of the total during the two weeks from June 14.

The health authorities are on alert over the possible rise in new cases as eased social distancing measures will take effect Thursday.

Under the four-tier distancing level to be introduced next month, the greater Seoul area will be under Level 2, allowing restaurants and cafes to open till midnight from the current 10 p.m.

Bars and other nightlife facilities will resume their operations, while the ban on gatherings of five or more people will be lifted to six people until July 14 in the capital area before the ceiling goes up to eight.

There will be no restrictions on business operations and the number of people allowed at social gatherings in other areas after the pilot run of new measures for the first two weeks of next month.

A total of 15.29 million people, or 29.8 percent of the country's 51.3 million population, have received their first shots of COVID-19 vaccines since the country started its vaccination program on Feb. 26.

The KDCA said 4.64 million people have been fully vaccinated.

South Korea is trying to inoculate 36 million people by September to achieve herd immunity in November, but it hopes it can reach the goal earlier than expected with the increased vaccine rollout.

The country currently uses vaccines from AstraZeneca, Pfizer, Moderna and Janssen.

Of the newly confirmed domestic cases, the capital area accounted for 73 percent, with 179 from Seoul, 157 from Gyeonggi Province and 30 from Incheon, 40 kilometers west of the capital.

There were 29 additional imported cases, down 15 from a day earlier, raising the total to 9,847.

Of the newly confirmed cases from overseas, 12 came from Indonesia, followed by Russia with five.

The number of patients in serious or critical condition came to 141, down six from the previous day.

The total number of people released from quarantine after making full recoveries was 146,675, up 335 from a day earlier, with 6,882 people being isolated for COVID-19 treatment. (Yonhap)