Police (left) and paramilitary police officers gather opposite the entrance to the closed Xinfadi market in Beijing. AFP

A district of Beijing was on a "wartime" footing and the capital banned tourism on Saturday after a cluster of novel coronavirus infections centred around a major wholesale market sparked fears of a new wave of COVID-19.

READ MORE

Worldwide coronavirus death toll at 424,757; cases exceed 7.66 million

Saudi Arabia reports 3,921 new cases of COVID-19

Concern is growing of a second wave of the pandemic, which has infected more than 7.66 million people worldwide and killed more than 420,000, even in many countries that seemed to have curbed its spread.

The virus was first reported at a seafood market in Wuhan, the capital of central China's Hubei province, in December.

Two women wear protective suits as they walk on a street near the closed Xinfadi market in Beijing on Saturday. AFP

Chu Junwei, an official of Beijing's southwestern Fengtai district, told a briefing on Saturday that the district was in "wartime emergency mode".

Throat swabs from 45 people, out of 517 tested at the district's Xinfadi wholesale market, had tested positive for the new coronavirus, though none of them showed symptoms of COVID-19, Chu said.

A city spokesman told the briefing that all six COVID-19 patients confirmed in Beijing on Friday had visited the Xinfadi market. The capital will suspend sports events and inter-provincial tourism effective immediately, he said.

One person at an agricultural market in the city's northwestern Haidian district also tested positive for the coronavirus that causes COVID-19 without showing symptoms, Chu said.

As part of measures to curb the spread of the virus, Fengtai district said it had locked down 11 neighbourhoods in the vicinity of the market.

Authorities closed the Xinfadi market at 3 a.m. on Saturday (1900 GMT on Friday), after two men working at a meat research centre who had recently visited the market were reported on Friday to have been infected. It was not immediately clear how the men had been infected.

Chinese paramilitary police march in formation outside the Xinfadi wholesale food market district in Beijing on Saturday. AP

"Preliminary judgment suggests these cases may have come into contact with a contaminated environment in the market, or were infected after being in contact with infected people. We cannot rule out subsequent cases in the future," said Pang Xinghuo, an official at the Beijing Center for Disease Control.

Beijing authorities had earlier halted beef and mutton trading at the Xinfadi market, alongside closures at other wholesale markets around the city.

Reflecting concerns over the risk of further spread of the virus, major supermarkets in Beijing removed salmon from their shelves overnight after the virus causing COVID-19 was discovered on chopping boards used for imported salmon at the market, the state-owned Beijing Youth Daily reported.