Cases of the new coronavirus pneumonia disease rose to 571 on the Chinese mainland as of Wednesday, including 95 in critical condition, and fatalities rose to 17, China's National Health Commission said on Thursday morning.

In addition, 393 suspected cases were reported as of Wednesday. All the reported deaths were in Hubei province, the epicentre of the outbreak.

Outside the mainland, Hong Kong, Macao and Taiwan each confirmed one case.

Thailand confirmed three cases, while the United States, Japan and South Korea reported one confirmed case each, the commission said.

Health authorities have traced 5,897 people who had close contact with the patients, and 969 of them have been released from medical observation, with 4,928 still under medical observation.

Earlier on the same day, the government of Wuhan, the epicentre of the outbreaks, announced a suspension of the city's public transport system, including buses, subway and ferry, and exits of airport and railway stations in the city, for disease control.

Upgraded measures are being taken to contain the outbreak of viral pneumonia within Wuhan to prevent it further spreading to other regions.

"We must be steadfast and strong to keep the outbreak within Wuhan. We'll urge Hubei province and the city of Wuhan to take the strictest measures for prevention and control," Li Bin, vice minister of the National Health Commission, said on Wednesday.

"Such measures include intensifying supervision of open air markets, minimising public activities, taking the strictest measures regarding people with fever and preventing the outbreak from further spreading," he said at a news conference organised by the State Council Information Office.

The Wuhan government required all people in public places such as hotels, restaurants, cinemas, parks, shopping centers and public transportation to wear masks to prevent the spread of the virus, according to an announcement on Wednesday night. The rule took effect immediately.

On Wednesday night, the Hubei provincial government reported 444 confirmed cases of the new coronavirus in Hubei alone as of 8pm. The death toll climbed from nine on Tuesday to 17.

On Wednesday, the disease further spread across the country. Health authorities in Shanxi, Fujian, Gui­zhou and Hebei provinces, as well as the Ningxia Hui autonomous region, confirmed their first infection cases.

In Macao, the region's government on Wednesday morning announced its first confirmed case. The patient is a 52-year-old female traveler from Wuhan.

In Hong Kong, health authorities confirmed its first case of coronavirus pneumonia, according to local media.

The 39-year-old man lives in Wuhan and arrived in Hong Kong on Tuesday evening. He was detected with fever and a cough at the high speed railway station in Hong Kong.

"Human-to-human transmission of the disease has appeared, and the virus is likely to mutate. There are risks of the further spread of the disease," Li said, adding that the ongoing traffic peak with the upcoming Spring Festival has increased the risks of it spreading, which requires a high state of alert.

China's National Health Commission had received reports of one confirmed case in Japan, one in South Korea and three in Thailand by Tuesday, Li said.

In the United States, the Centers for Disease Control and Prevention confirmed on Tuesday local time the first case in the country — a Washington state resident, according to Politico, a news website.

Gao Fu, head of the Chinese Centre for Disease Control and Prevention, said there is no evidence so far showing that a highly contagious virus has emerged.

He added that, based on current evidence, the virus originated from wild animals sold at a seafood market in Wuhan.

Emergency response mechanism activated

In Hubei, the provincial government announced early on Wednesday that it had activated its emergency public health response mechanism to effectively prevent the spread of the virus.

Strict quarantine measures are being taken on all suspected and confirmed cases, people in close contact with the cases and those who have been suspected of viral exposure, it said.

Body temperature testing points will be set up at all airports, railway stations and ports, and all passengers will be subject to testing before boarding. Suspected passengers will be sent to designated medical institutions, according to the announcement.

Local authorities will strictly control the number of outbound activities such as conferences, tours and visits, and large gatherings are banned.

Measures will also be taken to prevent the spread of the virus through public transport, and prevent sources of it from entering schools, according to the announcement.

Wuhan authorities announced on Wednesday that all local tourism agencies, including their branches outside the city, will suspend business and will not organize tours until Feb 8.

All tours scheduled to start after Jan 30 will be canceled.

The city government has also called for residents not to leave Wuhan and outsiders not to enter the city if there's no particular need, to reduce the risk of the virus spreading further.

Zhou Lihua in Wuhan and Xinhua contributed to this story.

This story was published in partnership with China News Daily