The city of 11 million is "swiftly launching comprehensive nucleic acid testing of all residents", senior Wuhan official Li Tao said at a press conference on Tuesday
Speculation emerged early in the pandemic that the virus could have accidentally leaked from the lab in Wuhan, although there was no evidence provided to back up that theory.
A team of investigators led by the World Health Organization visited a virus research laboratory in China’s central city of Wuhan and met with a prominent virologist there in its search for clues to the origins of the COVID-19 pandemic.
The experts spent about 3-1/2 hours at the heavily-guarded Wuhan Institute of Virology, which has been at the centre of some conspiracy theories that claim a laboratory leak caused the city’s first coronavirus outbreak at the end of 2019.
China has faced criticism at home and abroad for playing down the initial outbreak and concealing information when it first emerged in Wuhan in December 2019.
No full itinerary for the group's field work has been announced, and journalists covering the tightly controlled visit have been kept at a distance from team members.
A World Health Organization-led team investigating the origins of the deadly COVID-19 pandemic left a quarantine hotel in Wuhan on Thursday to begin field work, two weeks after arriving in the Chinese city where the virus emerged in late 2019.
The mission has been plagued by delays, concerns over access and bickering between China and the United States, which has accused Beijing of hiding the extent of the initial outbreak and has criticised the terms of the visit.
The group started a two-week quarantine on arrival on January 14 in the central Chinese city where the first known cluster of virus cases emerged in late 2019.