China has sealed off two cities south of Beijing, cutting transport links and banning millions of residents from leaving, as authorities move to stem the country's largest Covid-19 outbreak in six months.
The pandemic has so far broadly been brought to heel by Chinese authorities since its emergence in Wuhan in late 2019, with small outbreaks swiftly snuffed out using mass testing, local lockdowns and travel restrictions.
But Hebei province in northern China has seen 127 new Covid-19 cases, plus an additional 183 asymptomatic infections, in the past week.
The vast majority were found in Shijiazhuang, a city of several million in Hebei province whose surrounding areas take the total population to 11 million. Nine confirmed cases were in the neighbouring city of Xingtai, whose area covers 7 million people.
Residents of Shijiazhuang and Xingtai were banned from leaving the cities unless absolutely necessary, Hebei authorities announced Friday.
Officials vowed to "strictly control the movement of people and vehicles", with all residential estates placed under "closed management" -- a euphemism for lockdown.
Hebei residents were also banned from entering Beijing or leaving the province unless absolutely necessary.
People in four Hebei cities and fifteen counties surrounding Beijing must produce a negative nucleic acid test result taken within 72 hours to enter the capital, as well as proof of a Beijing address or workplace, officials said.
"The outbreak was imported from abroad, but the exact origins are currently under in-depth investigation by state, provincial and municipal experts," said Li Qi, head of the Hebei Centre for Disease Control and Prevention, at a press briefing Friday.
Li added that the outbreak is concentrated in Shijiazhuang's Gaocheng district, and other infections in the province were related to that outbreak.
Chinese officials have repeatedly tried to link recurrent domestic outbreaks to strains of the virus circulating overseas, suggesting that it had been brought back into China by methods such as returning travellers and contaminated imported food packaging.
Long-distance passenger vehicle transport in both cities was suspended as of Friday, and highways closed. Flights to and from Shijiazhuang have been cancelled, and trains suspended.
Footage from state broadcaster CCTV showed residents being swabbed by medical workers in hazmat suits at community centres in Shijiazhuang while queues outside stretched around the block.
Virus control staff stood guard at highways entering the city, which had mostly been blocked by barricades, the images released on Thursday showed.
Hebei province reported 33 new confirmed Covid-19 cases on Friday in addition to 51 from the day before -- pushing the nationwide daily total to the highest figure since July.
Schools have closed and officials have pledged to screen all residents of Shijiazhuang and Xingtai for the virus by Saturday.
So far, both cities have tested around 6.7 million residents in total, officials said Friday.
Staff were filmed giving injections of China's recently approved Sinopharm vaccine, which has a 79 per cent efficacy rate.
Three officials from the city's worst-hit Gaocheng district have been disciplined for apparent negligence in virus control, a sign of the pressure on local authorities to squash the virus wherever it emerges.