Shanghai on Wednesday extended its shut downs to some western parts of the city, earlier than scheduled, as it reported a total of 5,982 new local cases.

The financial hub of Shanghai, home to 26 million people, is in its third day of a lockdown authorities are imposing by dividing the city roughly along the Huangpu River, splitting the historic centre from the eastern financial and industrial district of Pudong to allow for staggered testing.

While residents in the east have been locked down since Monday, those in the west were officially scheduled to start their 4 day lockdown on Friday.

However, the city's southwestern district of Minhang, home to more than 2.5 million people, announced late on Tuesday it would suspend public bus services until April 5.

Several residents living in western districts also on Tuesday received notice from their housing committees that they would be stopped from leaving their compounds for the next seven days, for reasons such as pandemic control or because a neighbour had been a close contact of a positive case.

"We express our deepest thanks to all residents! We will resume normal life soon, but in the next period of time we ask everyone to adhere closely to pandemic control measures, do not gather, and reduce movements," said one notice seen by Reuters.

The city reported a record 5,656 asymptomatic COVID-19 cases and 326 symptomatic cases for March 29, up from 4,381 new asymptomatic cases and 96 new cases with symptoms for the prior day.

The lockdown has roiled auto production in the city too, as two major suppliers, Aptiv and Thyssenkrupp joined Tesla in shutting plants due to COVID control measures.

The Shanghai government said on its official WeChat account late on Tuesday that those who refused to comply with nucleic acid testing could be found legally liable and that it would punish any price gouging found, after people rushed to stock up on food and medical items in anticipation of the lockdowns.

The topic "Pudong pandemic" was one of the top trending items the Chinese Weibo social media platform. A widely shared video showed a robotic dog with a loudhailer strapped on to its back walking around the empty streets of a housing compound, reminding residents to take necessary precautions.