The number of infections linked to a front-line Army base has risen to 17, health authorities said Thursday, with a civilian counselor believed to have brought the virus to the military barracks.

Four more people -- one soldier, two career advisers and a family member of one of the counselors -- at the 220-strong unit in Pocheon, Gyeonggi Province, tested positive for the novel coronavirus, according to the Korea Centers for Disease Control and Prevention.

Kwon Jun-wook, deputy director of the KCDC, said the infections may have started from one of the career advisers. The adviser reportedly had visited the Army base on July 16.

“What we found so far is that the counselors did not properly wear masks,” he said at a briefing Thursday, stressing the importance of wearing masks when indoors, particularly in enclosed spaces.

Led by the central government, the Gyeonggi provincial government and the Army, an epidemiological inspection is underway into four more Army units the lecturers visited, he said. Some 400 soldiers from the units were and are being tested for the virus.

On Thursday, South Korea reported 59 new COVID-19 cases, with 20 imported from overseas and 39 locally transmitted, according to the KCDC. The total caseload rose to 13,938.

As for locally transmitted cases, 17 were registered in Gyeonggi Province, 11 in Seoul and two in Incheon. The cases are linked to several clusters: the Army unit in Pocheon, a nursing home in western Seoul, offices in southern Seoul, a church in southwestern Seoul and door-to-door salesfirms.

Four more people tested positive for the coronavirus from the church cluster. The confirmed patients attended the worship services despite showing symptoms, had meals together and sang hymns at the church choir without properly wearing masks, according to the authorities.

This came as the ban on church gatherings outside regular worship services, in place since July 8, is to be lifted Friday.

Of the 20 imported cases, 15 cases were detected while the individuals were under mandatory self-quarantine in Korea while five cases were identified during the quarantine screening process at the border. Ten were from Asia -- including five from Russia and three from Uzbekistan. Nine were from the United States and one was from Europe.

Imported cases remain a major concern for health authorities. In the past two weeks, 58.6 percent of COVID-19 cases have been imported from overseas.

Authorities said Thursday that three more Russian sailors aboard a ship docked in Busan had tested positive for the virus. A total of 46 cases reported here are traced to seven Russian-flagged vessels docked in the port city.

Also on Thursday, the government sent two military aircrafts to Iraq, where some 3,000 cases are being reported daily, on Thursday to bring some 300 workers home safely. Some 600 Korean workers are still in the Middle Eastern country for construction projects.

They are set to arrive at Incheon Airport on Friday morning.

A Korean worker diagnosed with COVID-19 died Wednesday while receiving medical treatment in Iraq, according to the Ministry of Foreign Affairs. Two Koreans died earlier of the coronavirus there. One Korean remains hospitalized for medical treatment.

So far, at least 45 people have tested positive for the virus among Korean nationals who returned home from a construction site in Iraq on a chartered flight on July 14, according to the KCDC data.

Upon their return to Korea, workers showing symptoms will be tested for the coronavirus at the airport and those with no symptoms will be tested once they settle in facilities where they will undergo self-quarantine for two weeks.

So far, 12,758 people, or 91.5 percent, have been released from quarantine upon making full recoveries, up 60 from a day earlier. Some 883 people are receiving medical treatment under quarantine. Eighteen people remain in serious or critical conditions.

The death toll stays unchanged at 297. The overall fatality rate stands at 2.13 percent -- 2.54 percent for men and 1.81 percent for women. The rate is much higher for those in their 80s and over -- 25.08 percent -- and those in their 70s -- 9.36 percent.

The country has carried out 1,500,854 tests since Jan. 3, with 21,418 people awaiting results as of Thursday.

(laeticia.ock@heraldcorp.com)