Authorities are speaking to passengers who shared a flight with men who had coronavirus from the Chinese city of Wuhan, where the outbreak originated, to Sydney.

NSW Health has confirmed that three people have the virus in the state, with another two under observation. The department is speaking to people daily who travelled with known patients to ensure that, if they begin to show any signs of infection, they are treated as soon as possible.

A Chinese health worker checks the temperature of a man entering a subway station during the Chinese New Year and Spring Festival in Beijing on Saturday. Credit:Getty Images

Border force officials are giving handouts to travellers arriving from all flights from China with information on the virus in both English and Chinese.

Chinese President Xi Jinping warned on Saturday of the "accelerating spread" of the disease, adding to fears about the scope of a crisis that has already claimed 56 lives and triggered emergency health measures in cities across China.