South Korea's daily new coronavirus cases fell below 600 on Tuesday on fewer tests over the weekend, but health authorities remained alert over a potential hike amid continued cluster inflections and spreading variant cases.

The country reported 528 more COVID-19 cases, including 506 local infections, raising the total caseload to 132,818, the Korea Disease Control and Prevention Agency (KDCA) said.

There was one additional virus death, raising the total to 1,904. The fatality rate came to 1.43 percent.

The country has been raising its guard against sporadic cluster infections across the nation amid the rising number of travelers enjoying warm weather.

Authorities are keeping a watchful eye on untraceable cases as well. Over the past two weeks, around 27 percent of newly added patients had unknown transmission routes.

The reproduction rate also currently hovers around one, indicating that a virus patient may infect at least one person.

The country has so far reported 1,113 cases of major muted strains of COVID-19, with southern cities, such as Ulsan, reporting the most variant cases.

Variant cases traced to Britain accounted for the largest slice of 904, followed by South Africa with 111 cases and Brazil with 11 cases. Those from India reached 87.

Authorities, meanwhile, said 1,039 South Korean nationals have returned home from India since May 4, with 38, or 3.2 percent, of them testing positive for COVID-19.

Health authorities will decide Friday whether to extend the current social distancing guidelines, which will be applied for a three-week period starting next week.

Currently, the greater Seoul area, home to more than half of the country's 52 million people, is under Level 2 social distancing, the third highest in the five-tier scheme.

Other areas have applied Level 1.5 social distancing, although some regional governments, including the southeastern port city of Busan, also maintain Level 2. Gatherings of five or more people are banned nationwide in principle.

While the country launched its vaccination program on Feb. 26, it has been sluggish in inoculating South Koreans amid the tight supply of jabs.

As of Tuesday, 1,039,642 people, or 2 percent of the country's population, have been fully vaccinated, receiving both doses of two-part vaccines.

A total of 3,745,934 people, or 7.3 percent, have received their first shots, up 12,006 from a day earlier.

AstraZeneca's vaccine has been given to 2.04 million people, while 1.69 million have received that of Pfizer.

Under the country's vaccination blueprint, South Korea aims to inoculate 13 million people by the end of June and achieve herd immunity by November.

The country said the amount of COVID-19 jabs available is estimated at 3.26 million doses. South Korea said some 438,000 doses of Pfizer's vaccine will arrive here Wednesday.

Health authorities said some 3.68 million additional doses of Pfizer's jabs will arrive here within the first half of the year.

Of the locally transmitted cases, 169 came from Seoul, and the surrounding Gyeonggi Province accounted for 134.

Daegu, 302 kilometers south of Seoul, added 23 more cases, and Gangwon Province saw 25 more infections.

Imported cases came to 22, raising the total to 8,773.

Of the imported cases, India accounted for five, followed by the Philippines, Japan and the United States with three each.

The number of patients in serious or critical condition came to 156, up five from the previous day.

The total number of people released from quarantine after making full recoveries was 122,631, up 468 from a day earlier. This indicates that 92.33 percent of the COVID-19 patients reported here have been cured.

South Korea has carried out 9,395,004 COVID-19 tests since last year, including 41,704 from the previous day. (Yonhap)