Eleven residential estates in south Beijing have been locked down due to a fresh cluster of coronavirus cases linked to a nearby meat market, officials said on Saturday.

Seven cases have so far been linked to Xinfadi meat market, six of them confirmed on Saturday, officials said. Nine nearby schools and kindergartens have been closed. 

The majority of China's cases in recent months were overseas nationals tested as they returned home, with the domestic outbreak brought largely under control after the disease first emerged in the central city of Wuhan last year.

But the new cases have prompted Beijing officials to delay the return of students to primary schools, and suspend all sporting events and group dining.

City authorities on Friday also closed two markets visited by one of the known cases.

The chairman of the Xinfadi meat wholesale market told state-run Beijing News that the virus was detected on chopping boards used to handle imported salmon.

Major supermarket chains including Wumart and Carrefour removed all stocks of salmon overnight in the capital, but said supplies of other products would not be affected, Beijing Daily reported Saturday.

AFP reporters saw dozens of police officers deployed at the two markets.

The novel coronavirus is believed to have jumped from an animal to humans at a Wuhan market that sold wildlife.

The first new case in Beijing after two months -- who had no recent travel history outside the city -- was reported on Thursday, and authorities confirmed two more infections the next day.

The other five cases reported Saturday were brought in from overseas.