Temporary laboratories for nucleic acid testing are seen at a stadium in Nanjing, capital of east China's Jiangsu Province, on July 27 (XINHUA) 

The eastern Chinese city of Nanjing is building six air-inflated labs to improve its nucleic acid testing capabilities after the recent resurgence of COVID-19 cases in the city.

Nanjing started building the six "Falcon" testing labs on Sunday. Three of the labs went into operation on Monday morning, and the others will be completed by the end of Tuesday.

When all six labs are in use, 180,000 sample tubes can be tested daily, and if mixed sample tests are carried out, 1.8 million people can be screened every day.

Nanjing, a mega-city with a population of more than 9.3 million, has added more than 100 locally transmitted COVID-19 cases since a few airport workers tested positive for coronavirus last week.

The city has launched its second all-inclusive nucleic acid testing campaign and urged residents not to leave the city unless necessary.