China began locking down most of its largest city of Shanghai as a coronavirus outbreak surges and amid questions about the economic toll of the nation's zero-Covid strategy, AP reports.

Shanghai's Pudong financial district and nearby areas will be locked down from early Monday to Friday as citywide mass testing gets underway, the local government said.

In the second phase of the lockdown, the vast downtown area west of the Huangpu River that divides the city will then start its own five-day lockdown on Friday.

Residents will be required to stay home and deliveries will be left at checkpoints to ensure there is no contact with the outside world. Offices and all businesses not considered essential will be closed and public transport suspended.