Tracing, quarantine, treatment, testing and screening are being carried out in an orderly and effective manner in Wuhan, Hubei province, to prevent and control the spread of the coronavirus, a senior health official said.

The city, which reported a cluster of COVID-19 infections originating at a weekend training course, added three new local positive infections in the 24-hour period ending on Thursday at noon, bringing the city's total to 26, including 20 confirmed cases and six asymptomatic carriers, said Peng Houpeng, deputy director of the Wuhan health commission.

All have been sent to Jinyintan Hospital for medical observation and treatment.

Of the new positive infections, two had attended the training course, and one was a close contact, Peng said at a news conference on Thursday.

"As of Thursday at noon, more than 1.14 million residents have provided samples for nucleic acid testing," he said.

Peng urged locals to pay special attention to personal hygiene to prevent infection and not leave Wuhan unless absolutely necessary.