Singapore has reported its first suspected case of the mystery Wuhan virus, involving a three-year-old girl from China who had pneumonia and a travel history to the Chinese city of Wuhan.

Countries are ramping up surveillance and response efforts to guard against the virus, which has hit at least 44 people in Wuhan.

The outbreak, which emerged last month, has revived memories of the Sars epidemic that started in southern China and killed hundreds around the world.

In Hong Kong, where five possible cases have been reported, the authorities have activated a newly created "serious response" level.

The city's health department added another thermal imaging system at the airport last Friday.

More staff have been assigned for temperature checks at the West Kowloon station that connects Hong Kong to the mainland.