South Korea reported 38 new coronavirus cases and one death on Monday, health ministry official Sohn Young-rae said in a news briefing.
Of those, 36 were locally transmitted cases in the capital Seoul.
A cluster of cases came from a group of small churches in Incheon, where 45 people who attended services have now tested positive for Covid-19.
Sohn said the virus spread at the churches because congregations were praying and singing hymns in a small space without wearing a mask.
South Korea has recorded at least 11,541 total cases and 272 deaths nationwide.