Beijing, Jul 25 (IANS): A second round of Covid-19 nucleic acid test was launched in Nanjing city, capital of China's Jiangsu province, following a resurgence of new confirmed cases.

The second round was launched on Saturday in the district of Jiangning, reports Xinhua news agency.

In the last 24 hours, the eastern Chinese city reported 12 new locally transmitted Covid-19 cases and four asymptomatic ones, local health authorities said on Saturday.

The first round of nucleic acid testing took place on July 21 after 17 airport workers tested positive for Covid-19.

The mega-city with a population of more than 9.3 million has classified 10 areas as medium-risk for Covid-19 and implemented closed management.

The municipal government has urged residents not to leave the city unless necessary.

Anyone leaving the city must produce a negative nucleic acid test certificate issued within 48 hours of their departure.

The rule does not apply to transit passengers.