Everyone in the business centre of Shenzhen will undergo three rounds of testing after 60 new cases were reported on Sunday.

All businesses except those providing essential goods such as food and fuel have been ordered to shut or operate from home.

Case numbers in China's latest infection surge are low compared to other countries and with Hong Kong, which reported more than 32,000 on Sunday.

But mainland authorities are enforcing a "zero tolerance" strategy and have locked down entire cities to find and isolate every infected person.