Travellers pass through a health screening checkpoint at Wuhan Tianhe International Airport. File photo/AP

The United States and other nations raced to get their citizens out of the locked-down Chinese city at ground-zero of a virus epidemic on Tuesday, as the death toll surged to 106 and the number of confirmed infections doubled to over 4,500.

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The deadly virus, which experts believe emanated from a wild animal market in the city of Wuhan last month, has triggered a desperate Chinese containment effort after spreading nationwide and to more than a dozen other countries.

Medical staff members carry a patient into the Jinyintan hospital in Wuhan, China. File photo/AFP

The government has sealed off Wuhan and other cities in central Hubei province, effectively trapping more than 50 million people, including thousands of foreigners, in a bid to contain the virus as the high-travel Lunar New Year holiday unfolds.

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As those trapped in Wuhan have become increasingly anxious, governments have scrambled to devise ways to safely get their citizens out of the city of 11 million.

The United States, France and Japan are among those to have announced plans for airlifts, but nearly a week after the lockdown the evacuations have yet to happen.

A chartered US-bound flight had been scheduled to leave Wuhan on Tuesday with consular staff and some American citizens.

But the State Department said that had been postponed to Wednesday, without giving a reason.

Passengers wear masks to prevent an outbreak of a new coronavirus in Hong Kong. File photo/Reuters

France has also said it intends to fly its citizens out of the city in the middle of this week, and Japan has similar plans.

Several other countries also were working to repatriate their people, while Germany said it was considering doing so.

The virus can be transmitted between people, although scientists have yet to determine how contagious it is and exactly the way it is spread.

In bids to stop huge numbers of people coming into close contact with each other, China has imposed tight transport restrictions in other parts of the country.

It has extended the Lunar New Year national holiday into next week.

A man wears a mask following the outbreak of a new virus in Toronto. File photo/AP

The education ministry on Tuesday also said the spring semester for schools and universities nationwide would be postponed, without giving a resumption date.

Death toll climbs

Despite the unprecedented measures, the virus has showed little sign of slowing down.

The national health commission on Tuesday said 26 new deaths occurred in the preceding 24 hours, bringing the nationwide total to 106.

Confirmed infections in China also jumped to 4,515, it said, up from 2,744 on Monday.

A quarantine officer monitors a thermal scanner on passengers landing from an international flight in Seoul. File/AFP

There were nearly 7,000 more cases suspected and awaiting confirmation, according to the commission.

The virus has also continued to spread around the world.

On Monday, the first infections were confirmed in Germany, Canada and Sri Lanka.

Fears over containment were heightened on Sunday when Wuhan's mayor, wearing a medical mask, revealed at a press conference that five million people had left the city for other parts of the country during the massive travel rush that precedes the New Year holiday.

President Donald Trump said the United States has offered Beijing "any help that is necessary" in combatting the virus.

People wear masks following the outbreak of a new virus as travellers land in Toronto. File photo/AP

But the United States, Turkey and Germany were among nations urging their citizens to "reconsider" all travel to China.

Malaysia on Monday banned visitors arriving from Hubei.

Landlocked Mongolia -- which is heavily dependent on trade with China -- took the drastic step of closing the border with its huge neighbour to cars.

Mongolia also cancelled classes until March 2 and suspended large public gatherings.