Chinese Premier Li Keqiang has visited Wuhan to "inspect and direct" efforts to control a deadly virus outbreak and promised reinforcements, as provincial authorities face accusations of not responding in time.

Li, clad in a blue protective suit and mask, thanked medical workers in Wuhan, the capital of Hubei province and epicentre of the coronavirus outbreak, as the death toll rose on Monday to 81.

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"Li ... thanked front-line medical workers for their all-out efforts in treating patients and urged them to pay attention to their own protection," Xinhua news agency said.

"He required efforts to guarantee medical resources supply, race against time to treat patients and ensure adequate market supply and stable prices."

He said 2,500 more medical workers would arrive in the next two days.

Li is the most senior leader to visit Wuhan since the outbreak began and he is in the head of the governing party's top leading body for the control of the novel virus epidemic.

China on Monday expanded sweeping efforts to contain the viral disease by extending the Lunar New Year holiday to keep the public at home and avoid spreading infection.

The coronavirus has killed 81 people in China while the total number of confirmed cases rose sharply to 2,744, with cases found in around a dozen countries as far away as France and the United States.

'Wuhan jiayou!'

Li inspected efforts to contain the epidemic and was shown on state television leading medical workers in chants of "Wuhan jiayou!" - an exhortation to keep their strength up.

He also visited the construction site of a new hospital due to be built in days.

On China's heavily censored social media, where dissent is typically suppressed, local officials have borne the brunt of mounting public anger about the handling of the virus.

Some lashed out at the Hubei governor, who had to correct himself twice during a news conference over the number of face masks being produced in the province.

"If he can mess up the data multiple times, no wonder the disease has spread so severely," one Weibo user said.

Wuhan Mayor Zhou Xianwang told state broadcaster CCTV the city's management of the crisis was "not good enough" - rare public self-criticism for a Chinese official - and said he was willing to resign.

The city of 11 million people is in virtual lockdown and much of Hubei, home to nearly 60 million people, is under some kind of travel curb.

People from Hubei have faced scrutiny within mainland China, as well, with many facing suspicion from officials about their recent travels.

"Hubei people are getting discriminated against," a Wuhan resident complained on the Weibo social media platform.

A county in northern China is offering 1,000 yuan ($145) to tipsters who report the presence of anyone from Wuhan who has not registered with authorities, local government TV said.