SEOUL, South Korea — New coronavirus cases in South Korea have reached the highest level in five months, and authorities fear infections are getting out of control in the Seoul region, which is home to half the country’s 51 million people.

Officials reported 166 newly confirmed cases Saturday. That was the highest since March 11, when South Korea reported 242 amid an outbreak in the southeastern city of Daegu and nearby towns.

With 103 new cases reported Friday, this is the first time since late March that the daily increase surpassed 100 two days in a row.

Officials say all but 11 of the new cases were local transmissions, and most were in the Seoul area.