A coronavirus cluster originating from a local Christian missionary group called the International Mission (IM) appears to be spreading nationwide, as officials said Thursday as many as 340 people have been infected so far.

According to local governments, 41 IM-related educational and research facilities in 13 metropolitan cities and provinces reported 269 COVID-19 cases out of their combined membership of 866 as of 10 p.m. Wednesday, marking an infection rate of 31.1 percent.

The International English Mission (IEM) School in the central city of Daejeon, an unauthorized school run by IM, accounted for 133 cases of the total, while two IM-affiliated schools in Gwangju -- the TCS International School and the TCS Ace International School -- have together reported 82 infections.

An IM-affiliated research center in Seoul's Gangseo Ward reported 12 COVID-19 patients. Notably, 39 IEM School students and teachers, who attended a winter retreat at a church in Hongcheon, 100 kilometers southeast of Seoul, from Jan. 16-25, have tested positive for COVID-19, heightening fears of virus transmissions among residents of the quiet Gangwon Province town.

Including non-Christian residents and families who have contracted the disease from members of the missionary group, the size of the IM cluster exceeds 340, the officials noted.

Indeed, there have been 82 confirmed cases among TCS school members in Gwangju, but 71 other people from the southwestern city and other areas have caught the virus from them.

A family of three in Ulsan, southeastern South Korea, has tested positive for the virus after visiting Gwangju's TCS International School last week. A church in Yangsan, near the southern port city of Busan, has reported six patients after its pastor visited the Gwangju school last week to give a lecture.

In Daejeon and Hongcheon, health authorities have conducted coronavirus tests on hundreds of local residents and merchants who appeared to have come into contact with infected IEM School members, though none of them have tested positive so far.

Local governments across the country have closed all 41 IM-related facilities and issued respective administrative orders asking that anybody who has recently visited any of those facilities immediately take the coronavirus test. (Yonhap)