Guangzhou is facing its toughest Covid-19 control challenge in three years, with nearly 2,000 local infections reported on Monday.
The surge came as cases across the country jumped to a six-month high.
Guangdong province reported a total of 185 confirmed local cases and 1,882 asymptomatic cases on Monday, with 122 confirmed cases and 1,813 asymptomatic cases in the provincial capital Guangzhou.
It was the second day in a row the city, which has a population of roughly 18 million, had reported more than 1,000 daily cases.
Guangzhou has imposed restrictions on parts of the city with severe outbreaks and moved more than 30,000 people into centralised quarantine. Daily mass testing is also required for those who have visited high-risk areas.
Over the weekend, Zhang Yi, deputy director of the Guangzhou health commission, said the city was “experiencing the most complex and severe Covid-19 prevention and control situation in three years”.
About 94% of the new cases in the past few days had been in the densely populated district of Haizhu, Guangzhou authorities said on Monday.
This week, the main battle against Covid-19 will continue to be fought in Haizhu, with more than 2,500 medical workers sent to the area to do door-to-door testing.
The Guangzhou government has also told landlords in the area to better inform tenants, urge them to comply with testing and be aware of their needs.
Authorities called for residents to stay indoors as much as possible to cut transmissions. They also warned that some people had violated the city’s prevention and control methods by moving fences to go outside or pass packages to one another.