Shanghai's authorities have said the city will remain under lockdown as it reviews results of an exercise to test all of its 26 million residents for Covid-19, Reuters reports.

The city began its two-stage lockdown on March 28, initially in Shanghai's eastern districts, and later expanded to cover the whole city. The curbs, which have massively disrupted daily life and business operations in China's financial hub, were initially scheduled to end at 5am local time on Tuesday.

"The city will continue to implement seal and control management and strictly implement 'staying at home', except for medical treatment," the city government said on its official WeChat account.

It did not give an indication of when the curbs might lift.

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