SEOUL (Reuters) - South Korea reported 166 new coronavirus cases as of Friday, of which 155 were domestic, prompting the reimposition of tighter social distancing curbs in Seoul area as authorities worried about the spectre of a fresh wave of the disease.

South Korea used invasive tracing and widespread testing to contain its first outbreak of the novel coronavirus, but Asia’s fourth-largest economy has experienced persistent outbreaks in recent weeks, mostly in the densely populated capital area.

For the second day in a row in over four months, the country has reported a sudden jump in locally transmitted cases, the Korea Centers for Disease Control and Prevention (KCDC) said.

The new cases took South Korea’s tally to 15,039 with 305 deaths by Friday midnight. The recent spike in infections are emerging in multiple church gatherings.

The authorities decided to upgrade the social distancing guidelines to second stage for Seoul and nearby Gyeonggi province, Prime Minister Chung Sye-kyun told a meeting on Saturday.

“We are facing a desperately dangerous situation that could lead to another wave of epidemics if we cannot overcome this crisis,” said Chung.

Health authorities had categorized social distancing rules in three stages - stage 1 being the least intense and stage 3 the toughest, where schools and businesses are urged to close.

Second stage limits indoor gatherings to below 50 and outdoor gatherings to below 100, and bans spectators in sports matches, disappointing fans who had just gone back into baseball and soccer stadiums after a five-week delay to the season.