University of Hong Kong public health expert Gabriel Leung says there are signs that the outbreak of the novel coronavirus will not come to an end when warmer weather arrives, unlike the 2003 Sars outbreak.

Leung said it was still unclear whether the coronavirus outbreak would prove more difficult to handle than severe acute respiratory syndrome, which killed almost 300 people in Hong Kong.

"What I have, in fact, seen is that places with very different climates than we have, such as Singapore and Thailand, they are enjoying weather that we usually enjoy in the summer, and yet their numbers are higher than ours," Leung said.

"So I wouldn't rely, as a principle means of combatting this particular epidemic, on climatic factors."

Hong Kong has reported 22 cases of the virus, one of which was fatal. Singapore has reported 30 cases while 25 people have fallen ill in Thailand.

More than 30,000 people have been infected with the virus on the mainland.

Leung, who is dean of medicine at HKU and chair professor of public health, said he would attend an urgent meeting of the World Health Organisation in Geneva next week.

The global health body has admitted it still doesn't know the source of the new coronavirus or its natural reservoir. It also says it doesn't fully understand how it's transmitted.