South Korean authorities have identified another 12 locally transmitted infections of Covid-19 linked to nightclubs in the capital Seoul.

Authorities are particularly worried that the virus was widely transmitted when people started returning to the bars and clubs of the Itaewon nightlife district from the end of April.

A total of 131 positive cases have emerged in this cluster since May 6, according to the South Korean Centers for Disease Control and Prevention (KCDC). The KCDC has conducted 35,000 tests — 15,000 alone on Wednesday — in an attempt to quickly trace and contain this outbreak.

Anonymous testing: The government is urging citizens who visited the area from April 24 through May 6 to get tested and is allowing people to remain anonymous. Some of the clubs where the virus spread are frequented by members of South Korea’s LGBT community, which sparked a backlash against gay people in local media and lead some to fear they would be outed.

The government of the local city of Incheon, which borders Seoul, said that 14 of the 131 cases are linked to one private academy instructor who visited clubs in Itaewon. The patient initially hid his movement but his GPS location tracking revealed his place of work in Incheon, a city bordering Seoul.

Vice Health Minister Kim Gang-lip said earlier that Incheon city announced it would pursue legal action against the tutor and if found guilty, he could be punished with up to two years in prison.

A total of 10,991 infections and 260 deaths have now been reported in the country, according to the Johns Hopkins University tally. The KCDC said Thursday that 29 cases were identified in the previous 24 hours, 26 of which were locally transmitted.