Governments need to implement "draconian" travel curbs to stop a mystery coronavirus in China becoming a global epidemic, a team of experts mapping the outbreak said Monday.
Scientists at the University of Hong Kong (HKU) presented a briefing warning that the spread of the deadly SARS-like virus that first emerged in the Chinese city of Wuhan was accelerating.
"We have to be prepared that this particular epidemic may be about to become a global epidemic," said Gabriel Leung, head of the team.
"Substantial, draconian measures limiting population mobility should be taken sooner, rather than later."
Leung leads a group of researchers who are mapping the virus, which has so far infected more than 2,700 people in China and killed 81 people.
While the epicentre remains in Wuhan and the central Chinese province of Hubei, it has since spread to some of the country's biggest cities -- including Beijing, Shanghai and Chongqing, and the southern cities of Shenzhen and Guangzhou.
"We are expecting to see epicentres of self-sustaining epidemics in these other major city clusters on the mainland," Leung predicted.
Given those cities have major regional and international transport links it was "highly likely" they would spread the virus further afield once those cities have self-sustaining outbreaks, he added.
The Wuhan virus has been detected in a dozen other countries -- as far afield as North America and Europe -- but only via a handful of people who travelled primarily from the epicentre in Wuhan.
The latest models from HKU warned that the number of actual infections was likely to be much higher than the official tolls, which only account for those who have been found and have tested positive.
HKU believes as many as 44,000 people may have been infected as of Saturday after evidence emerged suggesting people may be infectious even when they are not showing symptoms.
Leung said the number of infections would likely double every six days, peaking in April and May for those places currently dealing with an outbreak, although effective public health measures could bring that rate down.
The Chinese government has sealed off Wuhan and neighbouring cities, effectively trapping tens of millions of people, in a bid to contain the virus.
But some experts have warned those measures came too late, with millions leaving the region for the annual Lunar New Year holiday before the lockdown.
Leung said the lockdowns implemented by China were "absolutely correct", although he said the measures "may not be able to substantially change the course of this epidemic in the other major city clusters".
The HKU team is part of the World Health Organization's Collaborating Centre for Infectious Disease Epidemiology and Control, a network of academics around the world that help monitor new virus outbreaks.