A flu-like illness could travel around the world in 36 hours, killing 80 million people, experts have warned.
A team of experts led by a former chief of the World Health Organisation in The Global Preparedness Monitoring Board produced a report to try and encourage world leaders to take action, the Daily Mail reports.
In a report they released they said: "The threat of a pandemic spreading around the globe is a real one.
"A quick-moving pathogen has the potential to kill tens of millions of people, disrupt economies and destabilise national security."
The report, entitled A World At Risk, said current efforts to prepare for outbreaks in the wake of crises such as Ebola are "grossly insufficient."
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The GMPB is led by Dr Gro Harlem Brundtland, the former Norwegian prime minister and director general of the WHO, and Alhadj As Sy, the secretary general of the International Federation of Red Cross and Red Crescent Societies.
Recommendations it made in an earlier report have been "largely ignored" by world leaders, they said.
It wrote: "Many of the recommendations reviewed were poorly implemented, or not implemented at all, and serious gaps persist.
"For too long, we have allowed a cycle of panic and neglect when it comes to pandemics: we ramp up efforts when there is a serious threat, then quickly forget about the when the threat subsides."
They added that it was "well past time to act."
With large numbers of people criss-crossing the globe on planes each day, an equivalent air-borne outbreak to the 1918 Spanish flu pandemic could spread globally in under 36 hours, killing between 50 million and 80 million people, they estimate.
The global pandemic would be "catastrophic, creating widespread havoc instability and insecurity. The world is not prepared."
Many national health systems, particularly in poor countries, would collapse.
Axel van Trotsenburg, acting chief executive of the World Bank, and a member of the panel, said: "Poverty and fragility exacerbate outbreaks of infectious disease and help create the conditions for pandemics to take hold."
