Latest updates:

Shijiazhuang city has suspended intercity road passenger transport following the recent outbreak.

An expert group led by Ma Xiaowei, head of the National Health Commission, has arrived in Hebei to curb the outbreak. 

All kindergartens, primary and secondary schools in Shijiazhuang suspend face-to-face classes starting from Wednesday.

North China's Hebei province reported 20 confirmed COVID-19 cases and 43 asymptomatic carriers on Wednesday, all locally transmitted, bringing its total of recently confirmed cases to 39 and local asymptomatic carriers to 78, according to the provincial health commission.

Among the newly reported confirmed cases, 19 are in Shijiazhuang, Hebei's capital, and five of these have developed symptoms after previously being reported as asymptomatic carriers. Another case confirmed today is in Xingtai city. Among the 43 new local asymptomatic cases, 41 are in Shijiazhuang and two are in Xingtai.

The province has reported new local cases for four consecutive days since this new outbreak of COVID-19 was discovered on Sunday.

Xiaoguozhuang, a village in Shijiazhuang, Hebei province, was designated as a high-risk area for COVID-19 on Tuesday, the only such designation on the Chinese mainland, as the province adopted stricter measures to control the virus, including mass testing and suspending classes.

Experts from the Chinese Center for Disease Control and Prevention and the National Health Commission have arrived in Shijiazhuang city and Xingtai city to curb the latest outbreak, said Feng Zijian, deputy director of the China CDC.

Shijiazhuang, the provincial capital, will start citywide testing of all of its 10.39 million residents on Wednesday, Wang Jianfeng, a spokesman for the city government, said at a news conference on Tuesday night.

In Nangong, where confirmed cases were also found, the local government started mass testing for its around 500,000 residents on Sunday.

Hebei has seen COVID-19 cases surge since it reported the first confirmed case on Sunday in the latest outbreak. 

The source of the latest COVID-19 outbreak in Hebei is imported from overseas, and is highly likely to be from Europe, Feng said in an interview with China Central Television on Tuesday.

The cases in Shijiazhuang, Xingtai and Nangong have epidemiological connections, he said, adding that they were likely to have been infected from the same source.

Four areas in Shijiazhuang and Xingtai have been designated as medium-risk zones and placed under lockdown since Monday, and the province announced on Tuesday that it has entered a state of war against the virus.

On Tuesday, Liaoning province reported two new confirmed cases and Beijing reported one, according to the National Health Commission.

In Beijing's Shunyi district, all primary and middle school students, except those in the final years of junior and senior high, have moved to online classes to reduce the risk of infection. The district recently reported more than 10 confirmed COVID-19 cases.

Beijing will extend its quarantine period from 14 days to 21 days for people who travel from overseas to the capital, Xu Hejian, a city government spokesman, said at a news conference on Tuesday.

The city is facing a complicated situation in epidemic control because "some patients tested positive for COVID-19 after a 14-day quarantine", Xu said.