Zhengzhou authorities order mass testing and an effective lockdown for several districts in the city, affecting at least six million people.
China has ordered six million people into lockdown in a city where violent protests broke out at an iPhone factory over Covid-19 isolation policies and working conditions.
In the wake of the unrest, authorities ordered mass testing and an effective lockdown for several districts in the city starting on Friday.
Hundreds of workers took to the streets around the vast iPhone factory in Zhengzhou on Wednesday, confronting hazmat-clad personnel wielding batons in a rare display of public anger in China.
City centre residents cannot leave the area unless they have a negative Covid-19 test and permission from local authorities, and are advised not to leave their homes "unless necessary".
The restrictions will affect more than six million people but do not cover the iPhone factory, where workers have already been under Covid restrictions for weeks.
One worker told AFP news agency that the protests had begun due to a dispute over promised bonuses at the factory, run by Taiwanese tech giant Foxconn.
'Time to go home'
Foxconn on Thursday issued an apology, blaming a technical error in its payment systems for the salary issues and saying it "fully understands" the concerns of employees.
Apple said it had representatives on the ground at the factory and was "reviewing the situation and working closely with Foxconn to ensure their employees' concerns are addressed".
The world's largest Apple iPhone factory has been grappling with strict restrictions that have fuelled discontent among worker s and disrupted production ahead of Christmas and January's Lunar New Year holiday, as many workers were either put into isolation or fled the plant.
On Friday, Reuters news agency reported that more than 20,000 workers, mostly new hires not yet working on production lines, have already quit their jobs after taking their compensation from Foxconn.
Videos posted on Chinese social media on Friday also showed crowds and long lines of luggage-laden workers queuing for buses.
"It's time to go home," one person posted.
The curbs in Zhengzhou are part of China's national zero-tolerance approach to Covid-19, which involves gruelling lockdowns, travel restrictions and mass testing.
However, nearly three years into the pandemic, Covid-19 cases are now higher than they have ever been in China.
There were 31,444 domestic infections on Wednesday, the National Health Commission reported, the highest since the pandemic began.
The numbers are relatively small when compared with China's vast population of 1.4 billion or global caseloads at the height of the pandemic.
But under the zero-Covid policy, even small outbreaks can shut down entire cities and land the contacts of infected patients in strict quarantine.
The unrelenting zero-Covid push has given rise to fatigue and resentment among swathes of the population, sparking sporadic protests and hitting productivity in the world's second-largest economy.
Several cities including Beijing, Shanghai, Guangzhou and Chongqing have tightened Covid restrictions as cases have climbed.