The discovery has prompted fears within the US Government that the knowledge will fall into the hands of terrorists wanting to use it as a bio-weapon of mass destruction.

Some scientists are questioning whether the research should ever have been undertaken in a university laboratory, instead of at a military facility.

The US Government is now taking advice on whether the information is too dangerous to be published.

To see the graphic: The last outbreak - A deadly virus even before the latest twist

"The fear is that if you create something this deadly and it goes into a global pandemic, the mortality and cost to the world could be massive," a senior scientific adviser to the US Government told The Independent, speaking on condition of anonymity.