China broadened on Friday its unprecedented, open-ended lockdowns to encompass more than 20.5 million people as the government tries to contain a deadly new virus that has killed at least 26 people and infected about 830 others.

At the same time, Beijing confirmed two coronavirus deaths outside of Wuhan, the epicentre of the outbreak.

At least six cities were also added to the list of places under lockdown, all in central China's Hubei province, where the illness originated. That brings to at least 10 the number of cities covered in the lockdown order.

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In Wuhan, where the lockdown began early on Thursday, normally bustling streets, malls and other public spaces were eerily quiet. Masks were mandatory in public.

The railway station and the airport were closed, and ferry, subway and bus services were halted; police checked all incoming vehicles but did not close off the roads.

The other cities under lockdown as of Friday morning are near Wuhan, but authorities were taking precautions around the country.

In the capital, Beijing, major public events were cancelled indefinitely, including traditional temple fairs that are a staple of Lunar New Year celebrations.

The Forbidden City, the palace complex in Beijing that is now a museum, announced it will close indefinitely on Saturday.

Al Jazeera's Scott Heidler, reporting from Beijing, said the other big concern is when the travellers, who have already gone back to the provinces, will return to the cities after the holidays.

Most of the deaths and confirmed cases were concentrated in Hubei. But authorities on Friday also confirmed the first case outside the province.

The health commission in Hebei, a northern province bordering Beijing, said an 80-year-old man died after returning from a two-month stay in Wuhan to see relatives.

'Not yet a global emergency'

The vast majority of cases have been in and around Wuhan or people with connections in the city.

Outside the mainland, cases have been confirmed in Hong Kong, Macao, the United States, Japan, Taiwan, South Korea, Thailand, Singapore and Vietnam.

On Friday, Japan and South Korea reported at least one new case each of coronavirus infection.

Many countries are screening travellers from China for symptoms of the virus, which can cause fever, coughing, breathing difficulties and pneumonia.

The World Health Organization (WHO) decided against declaring the outbreak a global emergency for now. The declaration can increase resources to fight a threat but that can also cause trade and travel restrictions and other economic damage, making the decision politically fraught.

Staff members check body temperatures of the passengers arriving by a train from Wuhan to Hangzhou in Zhejiang province on Thursday [China Daily via Reuters]

The decision "should not be taken as a sign that WHO does not think the situation is serious or that we're not taking it seriously. Nothing could be further from the truth", WHO Director General Tedros Adhanom Ghebreyesus said.

"WHO is following this outbreak every minute of every day."

Chinese officials have not said how long the shutdowns of the cities will last.

While sweeping measures are typical of China's Communist Party-led government, large-scale quarantines are rare around the world, even in deadly epidemics, because of concerns about infringing on people's liberties. And the effectiveness of such measures is unclear.

"To my knowledge, trying to contain a city of 11 million people is new to science," said Gauden Galea, the WHO's representative in China.

Jonathan Ball, a professor of virology at molecular virology at the University of Nottingham in the United Kingdom, said the lockdowns appear to be justified scientifically.

The first cases in the Wuhan outbreak late last month were connected to a seafood market, and experts suspect transmission began from wild animals sold there. The market is closed for investigation.

China is eager to avoid repeating mistakes with its handling of SARS.

For months, even after the illness had spread around the world, China used hotels and ambulances to conceal the true number of cases and avoid WHO experts.

This time, China has been credited with sharing information rapidly, and President Xi Jinping has emphasised that as a priority.