Beijing reported four new confirmed cases of COVID-19 from 4 pm to 12 pm on Friday - totaling seven confirmed cases on Thursday and Friday, with all having close connection with the just closed Xinfadi agricultural products wholesale market in the city's Fengtai district.

Pang Xinghuo, deputy director of Beijing's Center for Disease Control and Prevention, said at a news conference on Saturday morning that except for one confirmed patient who went on a business trip to Qingdao, Shandong province, the other six patients had no history of being out of the capital or contacting people from Hubei or abroad.

She said these confirmed patients that all have been to Xinfadi or worked at the market in past days.

Besides, some samples collected from environment of these confirmed cases showed positive in nucleic tests, she said, adding that it's preliminary judgment that these cases may have exposed to the contaminated environment or infected people, which led to their infection.

It's possible that more cases will be found in the future, she said.

The municipal health authority has also tested 1,940 workers serving at the city's markets, among which 45 from 517 taken at Xinfadi and one from a market at Haidian district turned out to be positive.

These 46 people have no clinical symptoms so far and are under strict management and observations.

Also, 40 environmental samples from Xinfadi - out of 5,424 samples taken from the city's wholesale markets and supermarkets - tested positive for the nucleic tests.

"It's necessary to close the Xinfadi agricultural products wholesale market and we are working to trace the source of these cases," she said.