Beijing, January 23 (RHC)-- China told the 11 million residents of Wuhan on Thursday that they would no longer be allowed to leave their city, as the authorities step up efforts to halt the spread of a new coronavirus that first appeared in December and has now killed 17 people and infected 571.

"Without a special reason, city residents should not leave Wuhan," the central city's special command centre to combat the virus said, according to state media.   The move is meant to "effectively cut off the virus spread, resolutely curb the outbreak and guarantee the people's health and safety," the notice said, according to the official Xinhua news agency.

Train stations and the airport were closed, with buses, the metro system, ferries and long-distance shuttle buses also suspended.  All public gatherings have been cancelled until further notice.

The decision came as hundreds of millions of people are travelling across China for the Lunar New Year holiday, which starts on Friday, and state television said the number of confirmed infections had risen to 571.  Most patients are in Wuhan and the surrounding province of Hubei, but cases have appeared elsewhere in China and in countries including Thailand, South Korea and the United States.

In Geneva, the World Health Organization (WHO) delayed its decision on whether to declare the outbreak a global health emergency and asked an expert committee to continue meeting for a second day on Thursday.  “We need more information,” WHO Director-General Tedros Adhanom Ghebreyesus said.

The agency defines a global emergency as an “extraordinary event” that constitutes a risk to other countries and requires a coordinated international response.  When asked about Wuhan's public transport shutdown, WHO chief Tedros said authorities were probably acting to prevent transmission and mass gatherings.  “We cannot say they have done something unusual,” he said.

Reporting from Hong Kong, Al Jazeera's Adrian Brown said China was keen to show the WHO that it had the outbreak under control.  "If the WHO does declare a global public health emergency then that's going to harm China's international reputation," he said. "That's going to mean a big loss of face for China so I think China at this meeting is doing all it can to convince members that it does have this situation under control."