Beijing should stay highly cautious about the further spread of COVID-19 cases and enhance its nucleic acid testing capacities, according to capital city authorities.

"The city has contained the spread of the coronavirus outbreak, while it should maintain strict prevention and control measures," said Xu Hejian, spokesman for the municipal government, at a news conference on Wednesday afternoon.

The city reported seven new local confirmed cases of COVID-19, four suspected cases and one asymptomatic infection on Tuesday, according to the Beijing Center for Disease Control and Prevention.

Since the cluster outbreak on June 11 related to the Xinfadi agricultural wholesale market in Fengtai district, a major supplier of food to Beijing, 256 confirmed cases have been reported in the city.

Among the cases, 238 came from areas within 15 kilometers from the Xinfadi market, 194 within 10 kilometers and 160 within 5 kilometers, said Lei Haichao, director of the Beijing Health Commission.

He believed it is a sign that the outbreak has been well contained.

The city's latest coronavirus outbreak is considered faster than the previous one experienced in Wuhan, as the number of confirmed cases reached 100 in 11 days in Wuhan but did so in five days in Beijing, according to Lei.

The faster increase in the number of cases is also partly a result of enhanced prevention and control measures, including expanded nucleic acid testing capacities.

Among the confirmed cases, 137 have been found through nucleic acid testing conducted before the infected show related symptoms.

Twenty testing teams from 12 provinces, including Hubei, across the country have arrived in Beijing to help expand the testing.

Ten teams have begun working at 10 hospitals while the others will start their work in one or two days, said Guo Yanhong, an official with the National Health Commission, during another news conference on Wednesday.

The commission still reminds people to avoid unnecessary travel to and from Beijing, while the city's tourism authorities said on Tuesday that local travel agencies should not receive customers from outside Beijing and local residents from high and medium-risk areas.

There had been five and 38 areas in Beijing labeled as high-risk areas and medium-risk areas, respectively, by Tuesday, according to the State Council.

Pang Xinghuo, deputy head of the Beijing Center for Disease Control and Prevention, re-emphasized the importance of hand washing, social distancing and mask-wearing.