A chilling warning that tens of millions of people could be killed by bio-terrorism was delivered at the Munich security conference by the world’s richest man, Bill Gates

Gates, who has spent much of the last 20 years funding a global health campaign, said: “We ignore the link between health security and international security at our peril.”

How Bill and Melinda Gates helped save 122m lives – and what they want to solve next

Gates, the co-founder of Microsoft who has spent billions in a philanthropic drive to improve health worldwide, said: “The next epidemic could originate on the computer screen of a terrorist intent on using genetic engineering to create a synthetic version of the smallpox virus ... or a super contagious and deadly strain of the flu.”

US and UK intelligence agencies have said that Islamic State has been trying to develop biological weapons at its bases in Syria and Iraq. However, they have played down the threat, saying that the terrorists would need people with the necessary skills, good laboratories and a relatively calm environment free from the confusion and chaos of conflict zones.

Yet other security specialists say the threat from bio-terrorism has become more realistic over the past decade, particularly the past five years, with changes in molecular biology that make development of biological weapons more accessible.

Gates, making his first appearance at the Munich security conference on Saturday, said: “Whether it occurs by a quirk of nature or at the hand of a terrorist, epidemiologists say a fast-moving airborne pathogen could kill more than 30 million people in less than a year. And they say there is a reasonable probability the world will experience such an outbreak in the next 10 to 15 years.”

He added: “It’s hard to get your mind around a catastrophe of that scale, but it happened not that long ago. In 1918, a particularly virulent and deadly strain of flu killed between 50 million and 100 million people.

 “You might be wondering how real these doomsday scenarios really are. The fact that a deadly global pandemic has not occurred in recent history shouldn’t be mistaken for evidence that a deadly pandemic will not occur in the future. And even if the next pandemic isn’t on the scale of the 1918 flu, we would be wise to consider the social and economic turmoil that might ensue if something like ebola made its way into urban centres.”

Gates said advances in biotechnology, new vaccines and drugs could help prevent epidemics spreading out of control. “Most of the things we need to do to protect against a naturally occurring pandemic are the same things we must prepare for an intentional biological attack,” he said.

“Getting ready for a global pandemic is every bit as important as nuclear deterrence and avoiding a climate catastrophe. Innovation, cooperation and careful planning can dramatically mitigate the risks presented by each of these threats.”

The Guardian's Science Weekly Is emergent quantum mechanics grounded in classical physics? - Science Weekly podcast

Does strange quantum behaviour emerge from run-of-the-mill classical physics? If so, what does this tell us about the fundamental nature of reality?

The international community, Gates told the conference, needed to prepare for epidemics the way the military prepared for war: “This includes germ games and other preparedness exercises so we can better understand how diseases will spread, how people will respond in a panic and how to deal with things like overloaded highways and communications systems.”

The Bill and Melinda Gates Foundation published an Ipsos Mori poll saying that 71% of Britons aged between 16 and 75 are more concerned about the spread of infectious diseases such as Ebola or Zika than war with other nations. Just over two-thirds said they were concerned about war, while 83% said violent terrorist attacks were their main concern.