Hong Kong, Aug 25 (IANS): The Chinese metropolis of Chongqing has rolled out mass Covid testing in its central area amid a record heatwave, leaving millions of residents standing under the sun for hours as they struggle with extreme temperature and power shortage, media reports said.

Stringent zero-Covid measures enacted by the southwestern mega city to contain an emerging outbreak are the latest hardships for residents already reeling from a crippling heatwave, severe drought and blazing wildfires, CNN reported.

Chongqing reported 40 Covid cases on Wednesday, taking the the total to 146 since mid-August.

Authorities ordered more than 10 million people in the city's central urban districts to undergo mandatory Covid test on Wednesday, when the highest temperature in Chongqing soared past 40-degree Celsius, CNN reported.

More than 3,800 temporary testing sites have been set up across the central districts. Photos on Chinese social media showed residents forming long queues at the sites, with some passing out in the intense heat.

One widely-circulated video showed a street packed with hundreds of people apparently waiting in line for Covid test, most wearing face masks and some fanning themselves to relieve the heat. In the background, plumes of smoke from wildfires rose above the pale orange skyline, CNN reported.

"It's 43-degree C, the people of Chongqing are already stretched to the limit," a resident said on Weibo, China's Twitter-like platform.

To ensure residents in the central districts comply with the testing mandate, authorities turned the health code on everyone's mobile phone to orange. The code will turn green only after they complete the Covid test.

A green code is a prerequisite for going about daily life in China, where freedom of movement is dictated by a colour-code system imposed by the government to control the spread of the virus, CNN reported.