Nine people have now died of the Wuhan coronavirus in China, health officials say, with 440 confirmed cases.
Another 2197 cases of close contact with patients had been confirmed and there was evidence of "respiratory transmission" of the virus, National Health Commission vice-minister Li Bin told reporters.
As China vowed to tighten containment measures in hospitals, the World Health Organization (WHO) was due to hold an emergency meeting to determine whether the outbreak of the new coronavirus constituted a global health emergency.
The virus, originating in the central Chinese city of Wuhan in Hubei at the end of last year, has spread to Chinese cities including Beijing, Macau and Shanghai, as well as the United States, Thailand, South Korea, Japan and Taiwan.
The coronavirus originated from a market with illegal widelife transactions, Gao Fu, the director-general of China's Center for Disease Control and Prevention, told a news briefing, but it was adapting and mutating.
The Chinese government has been providing daily updates on the number of cases in a bid to head off public panic, as millions of people prepare to travel domestically and abroad for the country's Lunar New Year celebrations starting this week.
Hubei had been asked to minimise public gatherings and people across the country were urged to avoid densely populated areas in general, the health commission said. China also would step up cooperation with the WHO, Li said.
Officials found to have covered up infections would be a "sinner for eternity before the Party and the people", the Chinese Communist Party's Central Political and Legal Commission said in a post on its WeChat social media account that was subsequently deleted.
"I'm not sure that we could expect more of them at this stage in the outbreak, particularly when they are understandably focused on responding to the outbreak and trying to contain it ahead of the Chinese Lunar New Year celebrations," Adam Kamradt-Scott, an infectious diseases expert at the Centre for International Security Studies at the University of Sydney, said.
Fears of a pandemic similar to the Severe Acute Respiratory Syndrome (SARS) outbreak that started in China and killed nearly 800 people in 2002-2003 have roiled global markets, with aviation and luxury goods stocks hit particularly hard and the Chinese yuan tumbling.
The WHO said on Tuesday the new coronavirus was likely to spread to other parts of China and possibly other countries in coming days.
WHO spokesperson Tarik Jasarevic said new cases would appear as China stepped up monitoring. "If you increase surveillance and testing you are likely to get new numbers," he said.
Hong Kong's Cathay Pacific Airways, one of the airlines affected the most by the SARS outbreak, said it would allow flight attendants to wear a surgical mask while operating mainland China flights due to concerns over the new virus.
The Cathay Pacific Airways Flight Attendants Union said it had received a "tremendous" amount of messages from members concerned over catching the virus, and attendants on all flights should have the option to wear a mask.
"All of them are worried about the risk they are taking every time they go to work," the union said on its Facebook page.
Taiwan joined Australia in warning citizens to avoid travel to Wuhan, and airports around the world have stepped up screening of travellers from China.
"I want to call on our nationals please not to visit this region if not necessary," Taiwan President Tsai Ing-wen wrote on her Facebook page.
A Bank of Korea official said worries over the virus may impact domestic consumer spending.
Fifteen medical personnel are among those infected in China. Symptoms include fever, coughing and difficulty breathing. The viral infection can cause pneumonia and can be passed from person to person.
Though the origin of the virus has yet to be identified, WHO said the primary source was probably animal. Chinese officials have linked the outbreak to Wuhan's seafood market.