At least 13 new coronavirus infections traced to a major church in Seoul were reported on Friday, adding to concerns over a bigger outbreak, as the metropolitan area is facing a second wave of the infectious virus.

The patients, who are members of Wangsung Church in the southwestern ward of Gwanak, were found to have attended choir activities and an overnight church camp before testing positive, according to health authorities.

The first patient, a 31-year-old woman, was identified on Wednesday. Seven patients tested positive on Thursday and at least five more cases have been reported as of Friday afternoon.

The Seoul city government and health authorities are currently checking 41 church members and close contacts of the confirmed patients for possible infections.

The ward office of Gwanak has set up a temporary screening center in front of the church amid concerns that more infections could emerge among the church's some 1,700 followers.

The fact that some of the patients -- a high school teacher, an employee at the Four Seasons Hotel in central Seoul -- may have been in contact with students and hotel visitors has heightened concerns over additional infections.

City authorities have temporarily closed down and disinfected the church and a child care center run by the church. They have advised students who attended the Sunday service not to go to school.

They have also closed down the high school in Seodaemun ward as well as the Four Seasons Hotel's fitness center and sauna facilities, where one of the patients worked as a temporary employee.

On Friday, South Korea added 39 cases, raising the country's COVID-19 caseload to 12,602, according to the Korea Centers for Disease Control and Prevention.

Of the total, 27 were local infections, including 16 in Seoul and two in Gyeonggi Province. (Yonhap)