By Sangmi Cha and Josh Smith

SEOUL, Aug 28 (Reuters) - South Korean authorities stopped short of shifting the country up to the highest level of social distancing measures on Friday, despite recording another triple-digit increase in daily new coronavirus cases.

Prime Minister Chung Sye-kyun instead said the government would extend the current Phase 2 social distancing, which was due to expire this weekend, for at least another week.

"Phase 3 social distancing is the choice of last resort given the economic and social ripple effect," Chung said at a government meeting.

The Korea Centers for Disease Control and Prevention (KCDC) reported 371 new coronavirus cases as of midnight Thursday, bringing the country's total to 19,077, including 316 deaths.

After using aggressive tracing and testing to contain a large outbreak earlier this year, South Korea suffered a setback this month after a church cluster spread to a political rally.

Health authorities had reimposed Phase 2 social distancing rules on Aug. 16 in the Seoul metropolitan area, expanding the measures nationwide last week.

Earlier this week, Seoul officials ordered the closure of most schools in the capital and surrounding areas. Seoul has also mandated that masks to be worn in both indoor and outdoor public places, and has ordered places like churches, nightclubs, karaoke bars and other high-risk venues closed.

(Reporting by Sangmi Cha and Josh Smith; editing by Jane Wardell)