GENEVA (REUTERS) - The World Health Organisation (WHO) said on Thursday (Jan 23) it was "a bit too early" to declare a new coronavirus a global health emergency as China put millions of people on lockdown amid an outbreak that has killed 18 people and infected more than 630.

Health officials fear the transmission rate could accelerate as hundreds of millions of Chinese travel at home and abroad during week-long holidays for the Chinese New Year, which begins on Saturday.

“It is a bit too early to consider that this is a public health emergency of international concern,” WHO Emergency Committee panel chairman Didier Houssin said in Geneva.

WHO chief Tedros Adhanom Ghebreyesus said the organisation’s Emergency Committee of 16 independent experts had been divided in its conclusion.

“Make no mistake, though, this is an emergency in China. But it has not yet become a global health emergency. It may yet become one,” said Ghebreyesus.

He said China had taken measures which WHO believes are appropriate.

"We hope they will be both effective and short in their duration... For the moment, the WHO does not recommend any broader restrictions on travel or trade."

Peter Piot, a professor of global health and director of the London School of Hygiene and Tropical Medicine, said the outbreak was at a critical phase.

"Regardless of the decision not to declare this a Public Health Emergency of International Concern, intensified international collaboration and more resources will be crucial to stopping this outbreak in its tracks.

"National authorities and the World Health Organisation will need to continue to monitor developments very closely."

Giving details on infections in China, Chinese state television said 634 cases had been confirmed. By the end of Wednesday, China's National Health Commission confirmed 17 dead in the central province of Hubei.

Health authorities in Hebei, just south of Beijing, said on Thursday an 80-year-old man infected with the coronavirus had died there, marking the first confirmed death outside Hubei.

The previously unknown virus strain is believed to have emerged late last year from illegally traded wildlife at an animal market in the capital of Hubei province, Wuhan.

Most transport in Wuhan, a city of 11 million people, was suspended on Thursday and people were told not to leave. Hours later, neighbouring Huanggang, a city of about seven million people, announced a similar lockdown.

"The lockdown of 11 million people is unprecedented in public health history," said Gauden Galea, the WHO's representative in Beijing.

Related Story Coronavirus: What we know about the fatalities

The newly identified coronavirus has created alarm because there are a number of unknowns surrounding it. It is too early to know just how dangerous it is and how easily it spreads between people.

There is no vaccine for the virus, which can spread through respiratory transmission. Symptoms include fever, difficulty breathing and coughing, similar to many other respiratory illnesses.

Three research teams are to start work on developing a vaccine, a global coalition set up to fight diseases said.

As well as restricting movement, Wuhan plans to build a new hospital in six days to treat patients, Beijing News reported, citing a construction company source.

Other cities were also taking steps to contain the virus.

Nearby Ezhou shut train stations. Beijing cancelled large gatherings, including two Lunar New Year temple fairs, and closed the Forbidden City, the capital's most famous tourist attraction, to visitors until further notice.

The US State Department warned travellers to exercise increased caution in China as airports worldwide were screening passengers arriving from the country. Five people were being tested in Scotland for coronavirus and one person in Belfast showing symptoms was being treated, Sky News reported.

Chinese-ruled Hong Kong, which has two confirmed cases, is turning two holiday camps into quarantine stations as a precaution.

Taiwan has banned anyone from Wuhan from going to the island.

Chinese people had their own ways of protecting themselves.

"I go straight to where I need to go, and then I go home,"said 79-year-old Li Meihua, from behind a mask, on the streets of Shanghai. "I'm also maintaining a cleaner diet, I've turned vegetarian."