A new coronavirus is rapidly spreading in China, with state-run media reporting Wednesday that 17 people have died and about 550 patients have been infected in the country, up by more than 200 from the previous day, as cases have also been confirmed elsewhere in Asia and the United States.

Earlier in the day, the Chinese government announced at a press conference nine new deaths from pneumonia caused by the virus, which is believed to have originated in the central city of Wuhan and has appeared in Macau and Hong Kong a day after emerging in Taiwan.

On Tuesday, a man residing near Seattle was diagnosed with the new coronavirus after traveling to China, the U.S. Centers for Disease Control and Prevention said -- the first confirmed case in the United States and the first outside Asia.

Fears are growing that the number of infections will surge not only in Asia but all around the world, as many Chinese people are set to travel during the Lunar New Year holidays that start Friday.

The news conference was the first one held by the Chinese government over the new virus since reports of mysterious pneumonia cases in Wuhan surfaced in late December, and apparently signals Beijing's commitment to information disclosure.

The Cabinet-level National Health Commission pointed to an expert view that the novel virus -- the vast majority of cases of which have occurred in Wuhan -- may spread further through mutation, as transmission between humans has been confirmed.

The commission stressed that the country will step up international cooperation in containing the outbreak, amid reports the virus has spread to other nations, including Japan and Thailand.

Some analysts in China suspect that the new coronavirus could have originated in wild animals such as bamboo rats that were sold in markets for human consumption.

As of midnight Tuesday, the death toll in China had increased from six to nine, and the number of confirmed cases of respiratory problems due to the virus had risen from about 320 to 440, according to the government.

Li Bin, vice minister of the commission, told the press conference the recent jump in cases can be attributed to improved detection methods, accompanied by a deeper understanding of the disease.

All the deaths have occurred in Hubei Province, whose capital city is Wuhan, he added.

Given that millions of Chinese are likely to travel domestically and internationally for the New Year holidays, the government will implement stronger controls over movement in and out of Wuhan, and restrict public gatherings in the entire province, Li said.

In Wuhan, located around 1,000 kilometers south of Beijing, a Tokyo Olympics boxing qualifying tournament was scheduled to take place next month, but it has been canceled in order to protect the safety and health of those attending, organizers said Wednesday.

Thailand, South Korea and Japan have confirmed cases of infections, while Taiwan and the United States both reported on Tuesday their first cases of pneumonia caused by the new virus.

On Wednesday, Macau announced its first such case, while Hong Kong said the same day that a man arriving from Wuhan is strongly suspected to be infected.

North Korean authorities, meanwhile, blocked foreign tourists crossing the border from China on Wednesday as a preventive measure against the outbreak in its neighboring country, according to tourism companies.

In Taiwan, President Tsai Ing-wen announced a ban on entry into the island of tour groups from Wuhan. The ban, she said, will expand to other areas of China should the spread of the coronavirus pick up pace.

Coronaviruses usually cause common-cold symptoms affecting the nose, sinuses or upper throat, and are spread through sneezing, coughing or direct contact.

Some types, however, lead to more serious, sometimes deadly respiratory diseases like severe acute respiratory syndrome or Middle East respiratory syndrome, known as SARS and MERS, respectively.

Medical experts have called for people to wash their hands, gargle, and wear masks as a preventative step as influenza and colds are common in this period. In Beijing, masks have sold out at many supermarkets and convenience stores.

SARS emerged and raged in China in 2003 and then spread worldwide, killing 774 people.

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