The city eased many restrictions last week, after confining most of its 25 million residents to their homes since March as China battled its worst Covid outbreak in two years.

But the lockdown was never fully lifted, with hundreds of thousands in China’s biggest city still restricted to their homes and multiple residential compounds put under fresh stay-home orders.

The southwestern district of Minhang, home to 2.7 million people, will be placed under “closed management” on Saturday morning and all residents will be tested, district authorities said in a social media post on Thursday.

“The closure will be lifted after samples have been collected,” they added, without giving a specific time or date.

The statement also did not say what measures would be imposed if any district residents test positive.

Under China’s stringent zero-Covid approach, all positive cases are isolated and close contacts – often including the entire building or community where they live – are made to quarantine.

Shanghai reported nine new local infections on Thursday – none in Minhang.

The district’s announcement sparked fear among some social media users that the lockdown could be prolonged beyond Saturday if any cases are found.

“You need to clarify if (the lockdown) will really be lifted after samples are collected,” one user wrote on Weibo.

“If there are abnormal results after the tests, what will you do? Continue the lockdown?” asked another.

The lockdown in Shanghai – a major global shipping hub – had threatened to pile further pressure on already-strained international supply chains.

But the city has slowly come back to life in recent days.

Commuters are back on subways and buses as people return to working in their offices, while residents have gathered in parks and along the city’s historic waterfront.

But others are chafing under continued restrictions, with residents in one compound in the downtown Xuhui district protesting against the rules this week.

China’s capital Beijing, meanwhile, is transitioning more smoothly towards normality after shutting restaurants, gyms and subway stations last month to stamp out a smaller outbreak.