China on Wednesday reported its highest daily number of local coronavirus cases in months as mass testing campaigns uncovered a trail of Delta variant infections, prompting authorities to heavily restrict travel to major cities.

Local governments have tested entire cities and locked down millions, with the official figures on Wednesday revealing 71 new infections -- the most since January, but a low caseload despite the outbreak spreading to dozens of cities.

China is battling its biggest coronavirus outbreak in months
China is battling its biggest coronavirus outbreak in months AFP / STR

China had previously boasted of its success in crushing Covid-19, allowing the economy to rebound and normal life to return while swathes of the globe struggled to douse a pandemic that has killed more than four million people worldwide.

But the latest outbreak is threatening that record with nearly 500 domestic cases reported since mid-July.

The outbreak, which began when an infection among passengers on a flight from Moscow spread to airport cleaners in Nanjing, Jiangsu province, has exposed weaknesses in the country's already strict border containment measures.

Wuhan residents waited in long lines in the summer heat to get tested for the virus
Wuhan residents waited in long lines in the summer heat to get tested for the virus AFP / STR

China's immigration authority on Wednesday announced it would stop issuing passports and other documents needed for exiting the country in "non-essential and non-emergency" cases.

That does not yet mean an overseas travel ban for the Chinese public.

Foreign crew on hundreds of ships have been stopped from disembarking and changing shifts at Chinese ports.

Chinese officials have announced that the entire population of Wuhan will be tested for Covid-19 after the central Chinese city where the virus emerged recorded its first local infections in more than a year. The city of 11 million is "swiftly launching c
Chinese officials have announced that the entire population of Wuhan will be tested for Covid-19 after the central Chinese city where the virus emerged recorded its first local infections in more than a year. The city of 11 million is "swiftly launching comprehensive nucleic acid testing of all residents", senior Wuhan official Li Tao said a day after seven cases were detected. AFPTV / STRINGER

The central government has also ordered localities to cut off public transport and taxis in and out of areas hit by the outbreak, the transport ministry said at the same press conference.

Wuhan, where the virus first emerged in 2019, reported its first local infections in over a year this week and said Tuesday it was "swiftly launching" testing of all 11 million residents.

Long lines of residents waited at outdoor testing stations in the summer heat Tuesday, fanning themselves with paper forms while workers in hazmat suits took throat samples.

In Beijing, where the city government reported three new virus cases on Wednesday, authorities blocked entrances to a compound where one of the patients lived, while residents reached over fences to receive parcels from delivery drivers.

And the tourist destination of Zhangjiajie in central Hunan province, where infected travellers who had been in Nanjing attended a theatre performance, abruptly announced Tuesday that no one would be allowed to exit the city after it emerged as an infection hotspot.

Meanwhile, Shanghai is investigating a Delta case detected in an airport worker this week.

Authorities said on Wednesday the infection was not linked to other domestic cases and that they suspected the worker had been exposed after removing protective equipment while in a "contaminated area".

Coronavirus