Mass nucleic acid testing on all residents in Wuhan for COVID-19 will help protect people's health and fully resume social and economic order in the city, a senior official with the National Health Commission said on Friday.

Zeng Yixin, deputy head of the commission, said the mass testing is conducive to learning more about the scope of the epidemic in the city and carrying out targeted epidemic control and prevention measures.

Conducting nucleic acid tests on all Wuhan residents is no easy task in terms of mobilization and organization, he said at a news conference.

"We need to make sure people who have been tested earlier do not have close contact with those who will be tested later, and the accuracy of the test shall not be undermined by the large number of tests," he said.

Zeng said other local governments can also adjust epidemic prevention and control measures according to their real situation and testing capability.

Authorities in Wuhan launched a campaign to test all residents for novel coronavirus to quickly identify asymptomatic COVID-19 cases, after some new cases raised fears of a possible rebound of infections.

The city has reported several to a dozen asymptomatic cases every day recently and although these cases have been put under quarantine for treatment, they still have aroused concerns, according to a notice issued by the Wuhan government on Thursday.

The city has conducted nucleic acid tests on more than 3 million residents and will carry out the test on all residents that have not been tested before, it said.

Residents living in old communities, populous communities and communities with previous confirmed cases will be tested first, the notice said.

The city and district government will shoulder the costs for the tests, it added.