Beijing: Beijing banned high-risk people from leaving the Chinese capital and halted some transportation services on Tuesday to stop the spread of a fresh coronavirus outbreak to other cities and provinces.

China's financial hub of Shanghai demanded some travellers from Beijing be quarantined for two weeks, as 27 new COVID-19 cases took the capital's current outbreak to 106 since Thursday.

That makes it the most serious flare-up in China since February, stoking fears of a second-wave of the respiratory disease which emerged in the central city of Wuhan late last year and has now infected more than 8 million people worldwide.

The latest outbreak has been traced to the sprawling Xinfadi wholesale food centre in the southwest of Beijing where thousands of tonnes of vegetables, fruits, and meat change hands each day.

Beijing had designated 22 neighbourhoods as medium-risk areas as of Monday. Medium-risk areas are required to take stringent measures to block the potential entry of infection.

All high-risk people in Beijing, such as close contacts of confirmed cases, are not allowed to leave the city, state media reported on Tuesday, citing municipal officials.

All outbound taxi and car-hailing services have also been suspended. Some long-distance bus routes between Beijing and nearby Hebei and Shandong provinces were suspended.

Governments in many parts of China have imposed quarantine requirements on visitors from Beijing, concerned about contagion risks.

One suspected case who flew from Beijing to southwestern Sichuan province has become a confirmed case, health authorities said on Tuesday, and local officials are rounding up 111 close contacts for observation.

Hebei province reported four new cases, with two having come into direct contact with a virus carrier in the Chinese capital, and one being an operator at the Xinfadi market.

Shanghai on Tuesday started to require travellers from medium-to-high risk COVID-19 areas in China to be quarantined for 14 days.

The stakes are high for Shanghai, which has been invited to host two Formula One races this season. US airlines are also poised to resumes flights to the city.

While not in a Wuhan-style lockdown, the Chinese capital has gone into a "wartime" mode on a district level, with local neighbourhoods instituting 24-hour security checkpoints, closing schools and banning wedding banquets.

"Beijing will take the most resolute, decisive, and strict measures to contain the outbreak," Xu Hejian, spokesman at the Beijing city government, said at a press conference on Tuesday.

Overnight, some parts of Beijing including the city's old-style hutong neighbourhoods were fenced up, with entry and exit restricted to a few round-the-clock security checkpoints.

"We work as usual, but neighbourhood checks have become more strict," said Beijing resident Jin Rong, 23.

"I'm not worried that Beijing will be like Wuhan, because the current epidemic control measures have kicked in very quickly and have been very strict. People also have a strong sense of self-protection."

(With inputs from agencies)