Shanghai reported three new asymptomatic COVID-19 cases in precautionary zones in Qingpu district on Thursday, three days after the city announced it had achieved the status of "zero-COVID" beyond its quarantine and lockdown populations.

Precautionary zones are considered outside of quarantine and lockdown populations.

The Ze'an village in Xujing town of Qingpu district, where the three cases - two parents and their son - live has been classified as a medium-risk zone.

The restaurant, supermarket and two shopping malls the cases had visited have been temporarily closed for disinfection. The 18 close contacts and 20 secondary contacts have been identified, with all of them testing negative for COVID-19, said Zhao Dandan, deputy director of Shanghai Health Commission.

"We will stick to the 'dynamic zero-COVID' policy, normalize epidemic prevention measures and quick response, and strengthen controls according to different risk levels," said Zhao.

Zhang Yan, vice-governor of Qingpu district, said the three cases did not leave Xujing in the past 14 days and that the township had performed nucleic acid testing for all of its 228,588 residents on Thursday.