Authorities in the coastal metropolis of Xiamen, in Fujian province, told the 4.3 million residents on Tuesday not to leave the city, while major events were cancelled, schools switched to online classes, and restaurants and shopping centres were closed.

The measures came after 32 new coronavirus cases were discovered in the city on Monday, bringing the number of infections in Fujian province to more than 100 since last week.

The current outbreak originated in the city of Putian, which is in the north of Xiamen.

It is believed a man brought the virus back with him to Putian after a visit to Singapore. The man had returned to China on August 4, spent 21 days in quarantine and had tested negative for the virus nine times. But then, last Friday, a test came back positive.

Putian has also been in lockdown since the weekend.

The Chinese government is pursuing a zero Covid strategy.

With curfews, mass testing, contact tracing, quarantine and strict entry restrictions, the country has been able to keep the coronavirus under control.

Recently, local clusters of the Delta variant have been reported in places, but so far these have always been brought under control through strict measures.