South Korea's daily new COVID-19 cases rose by the smallest amount in more than two months due to fewer tests over the weekend as the country is preparing for eased virus restrictions starting next month amid an accelerating vaccination drive.

The country reported 399 more COVID-19 cases, including 360 local infections, raising the total caseload to 148,273, the Korea Disease Control and Prevention Agency (KDCA) said.

Monday's figure was sharply down from 452 cases on Sunday and 565 on Saturday. Daily cases usually rise from Wednesday as more people get tested in the week.

The latest caseload marks the first time the figure fell to the 300s since March 29, when the country reported 382 cases.

The country added three more deaths, raising the death toll to 1,988.

Health authorities are set to overhaul the country's social distancing scheme to be implemented starting next month after extending the current distancing rules until July 4 as vaccinations pick up steam.

Currently, the greater Seoul area, Daegu and Jeju Island are under the Level 2 distancing, the third highest in the country's five-tier system, while other regions are under Level 1.5 with nationwide restrictions on private gatherings of five or more people.

Under the revamped four-tier scheme, authorities plan to ease business curfews, with restaurants and entertainment facilities in the capital area permitted to operate until midnight, an extension from the current limit of 10 p.m.

Some virus curbs on sports facilities and concert halls have been eased starting Monday, with outdoor sports venues under Level 2 allowed to fill 30 percent of their seating capacity from the previous 10 percent.

A total of 11.83 million people, including 27,481 the previous day, have received their first shots of COVID-19 vaccines, accounting for 23 percent of the country's 5.12 million population, since the country started its vaccination program on Feb. 26.

The KDCA said 3 million people, or 5.9 percent of the population, have been fully vaccinated.

South Korea currently administers two-part vaccines from AstraZeneca and Pfizer as well as Johnson & Johnson's single-dose vaccine supplied by the US government earlier this month.

The country has also dispatched the Navy's 4,500-ton Hansando ship to waters near Jin Island, 472 kilometers south of Seoul, to vaccinate around 600 people who live on remote islands with Johnson & Johnson's vaccine aboard the ship.

Health authorities added they will start inoculating medical workers aged below 30 this week with 55,000 doses of Moderna's vaccine that arrived in the country earlier this month.

The country aims to vaccinate 14 million people with at least one vaccine dose by the end of this month and 36 million, or around 70 percent of its population, by September to achieve herd immunity in November.

KDCA Commissioner Jeong Eun-kyeong said in a briefing that the country will likely reach 13 million inoculations within this week at the current pace of vaccinations.

"There's a tremendous amount of vaccinations scheduled, so 13 million inoculations will likely be possible within this week," Jeong said.

Jeong added that the country needs to vaccinate at least 70 percent of its population with one dose to prevent the pandemic from spreading further.

A total of 47,003 cases of side effects after vaccinations have been reported, although some 95 percent of them were mild symptoms, such as a fever or muscle pain.

So far, 241 post-vaccination deaths have been reported, but the exact causes of the deaths remain unknown as causality could not be determined, health authorities said.

Of the 360 newly confirmed locally transmitted cases, 120 came from Seoul, 113 from Gyeonggi Province and 13 from Incheon, 40 kilometers west of the capital.

There were 39 additional imported cases, raising the total to 9,364.

The total number of people released from quarantine after making full recoveries was 139,022, up 441 from a day earlier. (Yonhap)