South Korea's daily new coronavirus cases fell below 1,800 on Sunday but still marked the highest tally for a Sunday to date, with the country extending its stringent virus curbs amid few signs of the situation abating.

The country added 1,729 COVID-19 cases, including 1,670 local infections, raising the total caseload to 210,956, according to the Korea Disease Control and Prevention Agency (KDCA).

The latest caseload is down from 1,823 reported Saturday but up from 1,704 on Friday. Daily cases usually fall over weekends due to fewer tests, but Sunday's cases showed there are no signs of the COVID-19 pandemic being contained.

The country added five more deaths from COVID-19, raising the death toll to 2,121.

As infections have steadily cropped up across the country, the authorities decided to extend the Level 4 distancing measures -- the toughest in the four-tier system -- for the wider Seoul area until Aug. 22, while non-Seoul metropolitan areas will remain under Level 3.

Health Minister Kwon Deok-cheol said extending the distancing rules was "inevitable" despite its impact on small merchants.

Kwon asked people to cancel or delay gatherings, saying that they are more likely to contract COVID-19 because of the highly contagious delta variant.

It was the first time that the total number of daily infections in non-capital regions surpassed 700.

Kwon called on people to strictly comply with containment rules, voicing concerns over "nationwide outbreaks" of COVID-19.

The Level 4 restrictions ban gatherings of more than two people after 6 p.m., place a 10 p.m. curfew on restaurants and cafes, and suspend the operations of nightclubs and other adult entertainment venues.

Under Level 3, cafes and restaurants can accept customers until 10 p.m., and only takeout and delivery services are available after that time. Private gatherings of five or more people are banned.

The daily caseload has remained above 1,000 since July 7 due to outbreaks centered in the greater Seoul area. Cases outside the capital area have also risen amid increased activities in the summer vacation season and the highly transmissible delta variant.

Since South Korea kicked off its vaccination program in late February, a total of 20.9 million people, or 40.7 percent of the country's 52 million population, have received their first shots of COVID-19 vaccines.

Around 15 percent, or 7.71 million people, have been fully vaccinated, according to KDCA data.

The country aims to administer a single vaccination shot to 36 million people, or 70 percent of its population, by September with hopes of reaching herd immunity in November.

In the latest domestic tally, Seoul reported 441 cases, the surrounding Gyeonggi Province added 456, and the western port city of Incheon confirmed 70 cases.

The southeastern port city of Busan posted 145 new cases, while the neighboring South Gyeongsang Province reported 117 more infections.

With the virus rapidly spreading into non-capital regions, Busan said it will raise its social distancing rules to the toughest level from Tuesday until Aug. 22.

Under the Level 4 rules, all beaches in Busan will be closed, city officials said.

In the first week of August, the average number of daily infections in Busan stood at 102.5, a sharp uptick from the previous week's 78.2.

There were 59 cases from overseas arrivals, which include South Korean nationals.

The total number of people released from quarantine after making full recoveries was 185,003, up 1,214 from a day earlier. (Yonhap)