TOKYO — A city in northern Japan has reported new coronavirus cases in nine people linked to the same karaoke bar and advised the elderly to refrain from karaoke singing.

Otaru Mayor Toshiya Hazama said Wednesday that the COVID-19 patients range in age from their 60s to their 80s and include an owner of the karaoke bar, seven customers and a relative of one of them.

Health officials in Otaru are tracing dozens of people who had close contact with the nine patients. Daytime karaoke singing, or “hiru-kara,” is popular among senior citizens on Hokkaido, the island where the city is located, and available at coffee shops.

In nearby Sapporo, about 60 recent virus cases were linked to the popular activity.

Tokyo reported 55 new confirmed cases Wednesday, the largest since early May. Officials said the increase was largely due to and expanded testing and does not immediately require restrictions to be reimposed on businesses.

There were about 20 other new cases reported from elsewhere in Japan, bringing the national total to more than 18,100 cases, with about 960 deaths.