Chinese health authorities sought to impose a quasi-quarantine Tuesday around Wuhan, advising people in the city of 11 million people not to leave, as they stepped up efforts to stop the spread of a mystery virus that has claimed six lives.

With confirmation that the pneumonialike coronavirus can be transmitted from person to person, and with hundreds of millions of Chinese packing onto public transport to make their annual pilgrimages home for the Lunar New Year, a new sense of panic has erupted here.

Long lines formed at pharmacies and convenience stores around the country as people rushed to buy surgical masks, with unlucky customers posting photos on social media of bare shelves.

People around the country cancelled their trips home for the Spring Festival, as new year celebrations are known, the most important holiday on the Chinese calendar.

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Kevin Frayer A Chinese girl wears a protective mask as she is held by a relative as they wait to board a train at Beijing Railway station before the annual Spring Festival on January 21, 2020 in Beijing, China. The number of cases of a deadly new coronavirus rose to nearly 300 in mainland China on Tuesday, as health officials stepped up efforts to contain the spread of the pneumonia-like disease which medicals experts confirmed can be passed from human to human.

"I don't really dare to go to the airport right now, or even to the movie theatre," said Xie Jing, 33, who works in advertising in Shanghai, where there have been two confirmed cases of coronavirus. She cancelled her planned trip home to Sichuan, where two cases are suspected.

"Everyone is being very careful at the moment in Shanghai. Everyone is wearing masks on the streets," Xie said.

The Geneva-based World Health Organization said it would call an emergency meeting Wednesday to decide whether to designate the outbreak as an international public health emergency. Australia and the Philippines are the latest countries with suspected cases of the infection – and Taiwan also confirmed one person there had caught it.

The virus was first detected on December 31 and was linked to a dirty food market in Wuhan, not far from one of the city's main train stations, where wild animals including wolf pups and civet cats had been on sale for consumption.

ITN The number of people infected by a new virus spreading from China into its neighbouring countries is on the rise.

The number of people in China confirmed to have the virus topped 300 on Tuesday, according to the National Health Commission, an increase of more than 70 from Monday. The vast majority of cases are in Wuhan, where Mayor Zhou Xianwang said six people have now died from the virus.

Wuhan's three major hospitals have 800 beds, but authorities said they would add 1200 beds to deal with the rising number of pneumonia cases. They also said they would foot the hospital bills for those infected.

Initially, doctors thought that the virus was not communicable between humans, but cases of infection across the country, including among people who have not been to Wuhan, proved that it can be passed on.

Some 60 people across 15 provinces are being monitored for possible infection,with cases found as far afield as Dalian in the northeast and Chongqing in the southwest, as well as in the metropolises of Beijing, Shanghai and Shenzhen.

Specialists are urging travellers not to move in and out of the central Chinese city.

"We hope people can avoid going to Wuhan if possible and that people in Wuhan can stay there," said Zeng Guang, chief epidemiologist of the Chinese Center for Disease Control and Prevention and the leader of a government team of experts responding to the outbreak. "This is not a call from the officials but a suggestion from us in the expert team," he said.

Still, he said it was "inevitable" that the virus would continue to spread as people moved around the country for the turning of the Lunar New Year on Saturday.

Fu Ting Pharmacist Liu Zhuzhen hangs up a sign reading "face masks are sold out" at her pharmacy in Shanghai.

The Ministry of Transport estimates that 400 million people will be on the move, making a total of 3 billion trips during this period.

A couple travelling from Beijing on Tuesday to see their son in Canada said they weren't too worried about the virus. "I think there are a lot of rational voices online telling us how to prevent transmission, so I think it's fine," said the woman, who gave her name as Mrs Li. Both she and her husband were wearing masks.

"We will take steps to prevent the virus being spread, but family affection is unstoppable, this is a tradition for Chinese people."

Health authorities added more infrared thermometers to Wuhan airport and train stations to check passengers for fever, while some hotels in the central Chinese city also began requiring temperatures to be taken before customers could check in. Outbound group tours have been restricted.

Traffic police began conducting random checks on vehicles travelling in and out of the city to make sure they were not transporting live birds or wild animals.

Ng Han Guan People wear face masks as they ride an escalator at the Hong Kong International Airport in Hong Kong.

Some airlines and travel agencies began to offer refunds to people travelling out of Wuhan or people with the virus – and some hotels have allowed people to cancel their reservations without penalty. At least two airlines flying to Wuhan have stocked their planes with masks.

The measures come after criticism that Wuhan authorities have been too lax in stopping the spread of the virus.

On Saturday, as the virus exploded in Wuhan, the city held potluck banquets to celebrate the looming holiday, attended by more than 40,000 families. News and photos of the event appeared Sunday on the front page of the state-run newspaper in Wuhan, but they were deleted from the Internet by Tuesday amid criticism about the lack of precautions.

The city had still planned to go ahead with 41 large-scale events for holiday celebrations, advertising them on Monday, but it announced Tuesday that they have been "postponed." Schools and universities are on break for Spring Festival, but more than 100 extracurricular "cram" schools in Wuhan have cancelled classes.

Quarantine was the most effective way to stop the virus from being transmitted, since it spreads by droplets from the nose and mouth, said Zhong Nanshan, leader of a group of experts at China's National Health Commission.

"Now our big concern is if a super spreader emerges," Zhong said Tuesday at a news conference in the southern province of Guangdong, using the term for a carrier who infects a disproportionately high number of people. A "super spreader" is thought to have passed the virus on to 15 medical staff members at a Wuhan hospital.

Although some hospitals have been stockpiling antibiotics, they are not effective against viruses. "There's no specific drug to treat the infection at the moment," Zhong said.

DAKE KANG/AP The Wuhan Huanan Wholesale Seafood Market, where a number of people related to the market fell ill with a virus, sits closed.

The Chinese Center for Disease Control and Prevention said it was the seventh type of coronavirus known to affect human beings. The previously known six viruses include Severe Acute Respiratory Syndrome (SARS) and Middle East respiratory syndrome (MERS), which are linked to animals.

Chinese health authorities have added this new type of pneumonia to the Class B list of infectious diseases, in the same category as SARS and HIV. But they said they would enforce the strictest controls, usually used for the most dangerous class A diseases such as cholera and the plague, to try to contain the coronavirus.

That meant authorities could forcibly quarantine people afflicted with or suspected to have the coronavirus – and would update the public on every single new case nationwide. Immigration authorities have also listed the new pneumonia on a list of certifiable infectious diseases.

In Australia, Queensland health authorities said they were monitoring a man who had been to visit family in Wuhan and then returned to Brisbane with symptoms of a respiratory illness. Australia, which receives about 1 million Chinese tourists a year, has now begun screening passengers arriving on the three weekly flights from Wuhan to Sydney.

In the Philippines, the Department of Health said it was monitoring a 5-year-old who arrived in Cebu from Wuhan with a fever and cough.

Cases have also been confirmed in Thailand, Japan and South Korea.

The Foreign Ministry in Beijing said there is not a complete ban on movement in and out of Wuhan.

"The Wuhan government has already taken measures to control the flow of people leaving Wuhan," said Geng Shuang, a spokesman at the ministry. "I understand when they are leaving or when they are entering, there will be checks, but there's not a complete ban of all people leaving."

Gregorio Borgia A notice explaining precautions to be taken by people traveling to Wuhan, China, is seen at a terminal of Rome's International Fiumicino airport.

The government was sharply criticised for downplaying or covering up the extent of the SARS virus, but experts said that Chinese authorities have learned many lessons in the 17 years since then.

"The new pneumonia in Wuhan reminds many people of the SARS epidemic in 2003," said a social media account run by the Central Political and Legal Affairs Commission, vowing not to repeat those mistakes.

"Self-deception will only make the epidemic worse and turn a natural disaster that was controllable into a man-made disaster at great cost," said the post, which was later deleted. "Only openness can minimise panic to the greatest extent."

Fortuitously, Wuhan is home to the highest biosafety level laboratory in China, a level-four facility that opened only two years ago and is designed for work on the most dangerous microbes, such as Ebola and Lassa fever.

When it opened, the lab was hailed as a "significant breakthrough" in building China's public health defense system, with state media calling it an "aircraft carrier" for virus research and a facility that put up "firewall virus protection" for the country of 1.4 billion people.