South Korea saw a slight decline in new coronavirus cases Wednesday, but cluster infections in Seoul and the surrounding area and imported cases continued to emerge.

The 101 new cases of COVID-19, detected Tuesday and down from 125 new cases a day earlier, brought the country's total cases to 9,887 and marked the 20th consecutive day that new infections have hovered around 100 or fewer additional cases, according to the Korea Centers for Disease Control and Prevention (KCDC). The death toll rose by three to 165.

A total of 52 additional cases were reported in Seoul and the surrounding region that includes Gyeonggi Province and the western port city of Incheon, bringing the total to 1,042, it said.

The number of daily new cases in the metropolitan area had so far hovered between 20 and 40. It breached 50 for the first time Wednesday, mainly due to mass cluster infection cases at major general hospitals and churches, the KCDC said.

Seoul reported 24 new cases, bringing the total to 474, partly due to a cluster infection at a church in the Guro district that has emerged as a new hotspot of cluster infections in the capital city.

Eight more people were newly confirmed as COVID-19 patients from the church, bringing the total number to 41, the KCDC said.

Meanwhile, all of some 500 people, including medical staff and patients, who had contact with a 9-year-old girl hospitalized at Asan Medical Center tested negative for the virus.

The girl, who was being treated for non-respiratory symptoms in a single-bed room, tested positive for the coronavirus Tuesday, raising alert over possible transmissions at one of the biggest hospitals in the country.

Still, the KCDC said medical staff members and the patient's parents have been put under self-isolation with another 43 patients at the hospital under cohort isolation.

Cohort isolation is the separating of a group of patients with the same infectious disease from others.

The cohort isolation comes as there have been several cases of patients testing positive for the new strain of virus after fully recovering and being released from quarantine, according to KCDC Director-General Jeong Eun-kyeong.

Gyeonggi Province reported 23 additional COVID-19 cases after a total of 13 people, up six from a day earlier, tested positive for the virus at Uijeongbu St. Mary's Hospital.

Daegu and North Gyeongsang Province, the nation's two worst-affected regions, reported 20 and two new cases, respectively, the KCDC said.

The KCDC said 35 percent of the newly confirmed COVID-19 cases over the past two weeks are from overseas, with another 34.9 percent from hospitals and nursing hospitals.

"An average of less than 10,000 people have entered the country every day since March 22 when quarantine measures were strengthened against foreign arrivals," Jeong said. The number of foreigners entering the country for a short-term visit is expected to dramatically decrease in the future.

The country also detected seven additional cases coming from overseas at quarantine checkpoints on Wednesday, raising the country's total number of imported cases to 560.

Starting Wednesday, all new arrivals to the country are placed in self-quarantine for two weeks as it struggles to stem a rise in new coronavirus cases coming from abroad.

"Starting today, all entrants from overseas are subject to a two-week quarantine measure," Vice Health Minister Kim Ganglip said at a press briefing. "Authorities will focus on thoroughly monitoring all quarantined entrants starting from airports to homes and other facilities to block imported COVID-19 cases."

The KCDC said the number of people entering the country shrank by 93 percent during the last week of March, compared with the first week of the same month.

Around 800,000 people entered the country during the first week, compared with 50,000 people during last week. Over 70 percent of them were South Korean nationals.

Those that do not have a place of residence here will be charged around 100,000 won ($82) per day for using public facilities.

In addition, all people in isolation must install a mobile app that allows authorities to monitor them in real time and ensure they are following the rules. They will also be able to report their condition via the app.

"All foreigners entering the country for a short-term visit must self-isolate for 14 days except for those visiting for national interests or public interests who will be faced with active monitoring," Jeong said.

South Korea has already been enforcing both a two-week quarantine period and virus tests for all long-term arrivals from Europe, regardless of symptoms. Entrants from the United States have also been required to self-isolate at home for two weeks.

In the face of community spread of the virus, the country on Tuesday again pushed back the new school year, with the introduction of online classes. The opening of kindergartens and child care centers has been delayed indefinitely.

The KCDC said 159 more people were fully recovered and released from quarantine, bringing the number of the total cured people to 5,567.

As of Tuesday 4,155 are receiving treatment, down from 4,216 the previous day, according to the KCDC.

The virus was first detected in the country on Jan. 20, it said. (Yonhap)