Beijing will require all residents living and working in 12 districts to take three consecutive nucleic acid tests on May 3, 4 and 5 to curb the COVID-19 epidemic and cut transmission, a senior official said on Monday.

The districts include Dongcheng, Xicheng, Chaoyang, Haidian, Fengtai, Shijingshan and Fangshan, Li Ang, deputy director of the Beijing Municipal Health Commission, said at a news conference on Monday afternoon.

"The city has conducted several rounds of mass nucleic acid tests since April 25, which has effectively helped to discover the infection risk and cut the virus spread during this round of the outbreak," he said.

The city completed its third round of mass nucleic acid testing on April 29 and 30, covering around 21.8 million residents. Two rounds had been done previously.

Beijing reported 41 new locally transmitted confirmed cases and nine new asymptomatic carriers between 3 pm on Sunday and 3 pm on Monday, bringing the city's total infections to 400 across 14 districts since April 22, according to the Beijing CDC.

Among the new infections, 45 were reported from the controlled zones and five were found during the mass nucleic acid tests, Pang Xinghuo, deputy director of the Beijing CDC, said at the news conference.

Of the 400 infections, Chaoyang registered 156 cases, followed by Fangshan with 103 cases, according to Pang. During the same period, Tongzhou reported 43 cases and Fengtai had 29 cases, she added.

"After the analysis of the confirmed cases, the Beijing CDC found that many clusters were caused by people dining together in restaurants and many of the people hadn't been vaccinated, which added to the infection risks," she said.

The infected people went to a wide range of places in the city, which also caused an increasing number of infections, she added.

The Beijing CDC has completed the gene sequencing of hundreds of samples from local patients during the latest outbreak and the results showed that the infections involved the Omicron variant and are part of two different transmission chains.

Due to the increasing number of COVID-19 cases, two more residential communities in Chaoyang and one more community in Fangshan were designated as high-risk areas on Monday.

As of Monday afternoon, Beijing had 10 high-risk areas and 26 medium-risk areas.

During the five-day May Day holiday, which began on Saturday, the municipal authority has required that all residents must present a negative nucleic acid test taken within 48 hours if they wish to enter public places, including scenic areas, hotels and homestays.

All restaurants in the city suspended dine-in services and instead are offering delivery services from May 1 to 4, as required by the commerce bureau.