Beijing has recorded 36 new locally-transmitted coronavirus cases, amid fears of a second wave in the Chinese capital.
Another 36 cases were also recorded on Saturday. The city had previously seen no new cases in more than 50 days.
The country's Vice Premier Sun Chunlan called on officials to take "decisive measures", warning that the risk of further spread remained high.
The outbreak has been linked to the city's largest wholesale market, reports the BBC.
The general manager of the market has been dismissed, along with other local officials.
Three other provinces - Liaoning, Hebei and Sichuan - have also reported confirmed or suspected cases connected to Beijing.
Local media reports say the virus was discovered on chopping boards used for imported salmon at the market, prompting major supermarkets in Beijing to pull the fish from their shelves.
According to China's National Health Commission, Beijing recorded one new virus case on Thursday and six on Friday - the first cases in almost two months.
On Saturday, 36 new local cases were recorded in Beijing, all related to Xinfadi market - which has been described by state media outlet CGTN as the biggest wholesale market in all of Asia.
The market was quickly placed under lockdown and restrictions were imposed in 11 nearby neighbourhoods.
On Monday, ten more neighbourhoods around the market were restricted, said CGTN. No visitors or deliveries are allowed, but residents can come and go.
Schools and nurseries near the market were told to shut and the re-opening of primary schools, originally scheduled for today, has now been postponed, reported the Global Times.