Shanghai authorities have again tightened anti-virus restrictions, just as the city was emerging from a month of strict lockdown due to a COVID-19 outbreak.
Notices issued in several districts said residents were ordered to stay home and are barred from receiving non-essential deliveries as part of a "quiet period" lasting at least until Wednesday.
The tightened measures could be extended depending on the results of mass testing, the notices said.
"Thank you for your understanding and co-operation. Together we can lift the lockdown at an early date," said one notice issued in the city's Huangpu district and posted online.
It was not clear what prompted the renewed tightening, with numbers of new COVID-19 cases in the city continuing to fall.
Shanghai on Monday reported 3947 cases in the previous 24 hours, almost all of them without symptoms, along with 11 deaths.
Authorities have been gradually lifting isolation rules on the city's 25 million residents, but the new orders appear to be returning to conditions at the early stage of the outbreak.
Shanghai originally ordered mass testing along with a limited lockdown, but extended that as case numbers rose.
Thousands of residents have been forced into centralised quarantine centres for showing a positive test result or merely having been in contact with an infected person.
In Beijing, authorities closed down the largest city district, with residents told to stay home and stores closed.
Beijing has ordered daily testing of all residents, closed parks and other leisure venues and limited restaurants to takeout business only.
Companies and investors worry the ruling Communist Party's "zero-COVID" strategy that closed most businesses in Shanghai and other industrial centres is disrupting global trade and activity in autos, electronics and other industries.