BEIJING — Authorities have completed a third round of coronavirus tests in the northeastern border city of Manzhouli, where three new cases were reported on Monday.

The city government said testing on 200,745 people wrapped up on Saturday following two earlier rounds last month. No new positive cases were found and the three announced Monday were among those previously isolated as suspected cases, authorities said. Testing has been accompanied by travel restrictions and the quarantining of suspected cases and close contacts of those infected.

China reported a total of 15 new cases on Monday, 12 of them brought from outside, bringing the mainland’s total to 86,634 with 4,634 deaths. Hospitals are currently treating 281 people for COVID-19 while 231 people are being monitored in isolation after having tested positive for the virus while showing no symptoms.

The virus, meanwhile, continues to surge in Hong Kong, with another 95 cases reported on Sunday, bringing the semi-autonomous Chinese city’s total to 6,897 with 112 deaths. Authorities there have tightened restrictions on the city’s 7.5 million people, including banning most social gatherings to just two. The surge in cases has also led to the suspension of plans to open a “travel bubble” with Singapore, underscoring the impact the outbreak has had on the city’s economy.