Chinese city Chegdu entered lockdown on Thursday, trapping 21.2 million people within the area as Covid-19 cases surged.
The region is set to undergo four days of Covid testing across the city. All residents were ordered to remain at their homes from 6pm on Thursday, with one person per day allowed outside to shop for essentials.
The announcement comes as a blow to hopes of improved Chinese productivity, following disappointing productivity figures over the past few months.
Chengdu is the largest city to enter lockdown in China since Shanghai was shut down for two months earlier in 2022.
Southern Chinese cities have implemented a selection of restrictions to clamp down on Covid cases, including work-from-home schedules and large audience venues suspended from operation.
China has maintained a “zero-Covid” policy since the pandemic broke in 2020, which has seen the country close its borders to tourists and outside visitors in many regions.
Chengdu residents working in vital manufacturing and capable of managing on closed campuses were exempted from work-from-home restrictions.
The Chinese government did not specify an estimated end date to the lockdown.