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.
A total of 79 cases are linked to the Xinfadi market, said the Global Times.
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 new cases 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 lockdowns were also imposed in 11 nearby neighbourhoods.
On Monday, ten more neighbourhoods around the market were shut down, said CGTN.
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.
AFP - The outbreak has been linked to a market like this one
Some 10,000 market staff will be tested for the virus.
The chief epidemiologist of China's Centre for Disease Control and Prevention (CDC) said the virus strain found in Beijing did not resemble the type circulating across the rest of the country, suggesting it might have been brought in from elsewhere.
This potential new wave of cases came as normal life had begun resuming across Beijing and most parts of China.
People had cautiously returned to workplaces and students back to schools - though virus restrictions still remained in place.
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