Hunchun, a border city in Yanbian Korean autonomous prefecture of Jilin province reported a new locally transmitted COVID-19 case on Tuesday and another seven positive tests for the virus, the local government said.

The male confirmed case left Hunchun for the city of Yanji in Yanbian by train at 7:36 on Monday morning and returned from Yanji at 10:39, Cui Donghui, deputy secretary general of the prefecture, said at a news conference on Tuesday afternoon. He tested positive for the virus from the test conducted after he got off the train in Hunchun.

He was then diagnosed as a confirmed case with mild symptoms.

All eight cases have been sent to a designated hospital for quarantine and treatment and a total of 452 close contacts have been traced as of 1pm Tuesday.

"Mass nucleic acid testing in Hunchun, covering all local residents, has started and is expected to be completed within 24 hours," Cui said.

Residents of Hunchun were asked not to leave home unless necessary, according to a statement released by the city's epidemic prevention and control headquarters.

The city has suspended all public transportation services, including buses, long-haul buses and taxis.

No vehicles are allowed to leave or enter the city except for those engaged in transporting goods or involved in epidemic prevention and control, medical aid and emergency rescue.

All senior high schools have been put under lockdown management, while kindergartens, primary schools, junior high schools and vocational schools will be suspended and online courses will be provided during the period, the statement said.

Public venues in the city, including educational institutions, entertainment facilities and private clinics, suspended services from Tuesday.