China has reported 100,871 symptomatic cases and fewer than 5,000 deaths since the virus first emerged in the city of Wuhan in late 2019.
China on Saturday reported its highest number of new coronavirus cases in four months, as officials raced to contain the outbreak in several regions, including the city of Xi'an, where millions are still under lockdown.
China, where the coronavirus was first detected in late 2019, is on high alert for new infections as it prepares to hold the Winter Olympics in the capital Beijing in February.
According to a statement by the National Health Commission, out of 140 new infections, 87 were locally transmitted, up from 55 a day earlier.
Most were in Xi'an, the northwestern province of Shaanxi, where 13 million residents have been locked down since Thursday.
On Christmas Eve the city recorded its highest daily count in a year, with 75 domestic cases, according to the local health bureau.
While China has minimized cases - thanks to a zero-Covid strategy of tight border restrictions, lengthy quarantines and targeted lockdowns - cases have been bubbling up in recent weeks.
Footage from state broadcaster CCTV showed long queues outside Xi'an testing centers on Saturday as officials rushed to stamp out the latest flare-up.
Under strict lockdown rules, since Thursday, all homes in Xi'an have been allowed to send only one member out every two days to buy essentials. Residents need special permission from their employer or local authorities to leave the city.
Xi'an has recorded 330 locally transmitted symptomatic cases since the first case was reported on 9 December 2021, compared to outbreaks elsewhere in the world.
But some 26 Xi'an government officials have been punished for lapses in virus containment, China's disciplinary body said on Friday.
Local officials who are deemed to have failed to control the virus in their region are routinely sacked or reprimanded under Beijing's strict zero-Covid approach.
Xi'an's cases have so far spread to five other cities, including Beijing, according to state media, fueling fears about how quickly the virus could spread geographically across the country.
China has reported 100,871 symptomatic cases and less than 5,000 deaths since the virus first emerged in the city of Wuhan in late 2019.