Beijing will conduct more rounds of mass nucleic acid testing starting Saturday to curb the epidemic and cut transmission chains, a senior official said on Friday.

The authority requires all residents living and working in districts including Chaoyang, Fengtai and Fangshan, as well as other sub-districts and counties that have reported new COVID-19 cases since April 25 to take another two consecutive nucleic acid tests on Saturday and Sunday, said Li Ang, deputy director of the Beijing Municipal Health Commission, said at a news conference on Friday 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.

During the last three rounds of the mass nucleic acid tests from Tuesday to Thursday, around 20.74 million residents completed the tests and five sample tubes showed positive. The controlled measures and epidemiological investigations have started on samples testing positive, according to Li.

Chaoyang, the hardest-hit district in the outbreak, will conduct one more round of mass nucleic acid tests of all its residents on Monday in addition to the two rounds announced by the health commission, according to Yang Beibei, the district's deputy head, at the news conference on Friday afternoon.

Chaoyang district registered 251 cases, the most in the outbreak since April 22.

Haidian district, which has reported five new locally transmitted cases between 3 pm on Thursday and 3 pm on Friday and total infection of 28 since April 22, announced on Friday evening that it will also conduct three rounds of mass nucleic acid tests on Saturday, Sunday and Monday.

Shijingshan district in western Beijing, announced on late Friday that it will conduct three rounds of tests in major sub-districts between Saturday and Wednesday.