Beijing is still at a critical stage in its fight against the latest COVID-19 outbreak, a health official of the city said.

Beijing reported 78 new COVID-19 infections during the 24 hours ending at 3 pm on Saturday, said Pang Xinghuo, deputy director of the Beijing Center for Disease Prevention and Control, at a news conference on Saturday.

Among the new infections, 70 were reported in controlled zones and two were found during testing at the community level, Pang said. The city has logged a total of 688 newly confirmed cases in the latest outbreak, which began on April 22. 

Epidemiological investigations and genetic sequencing revealed two separate transmission chains, one from Chaoyang district involving 675 infections and another involving a hospital in Fengtai district where 12 cases originated.

Pang said since viral transmission chains have not been completely cut off at the community level, the city should take faster and stricter actions to curb the spread of the virus.

Two residential communities in the city's Tongzhou district have been designated as high-risk areas for COVID-19 starting Saturday. The city now has 20 high-risk areas and 34 medium-risk areas.