A super-strain of bird flu that could infect and wipe out millions has been developed in a laboratory.
Dutch scientists who created the 'Armageddon virus' say it is "probably one of the most dangerous viruses you can make".
Their research focused on what it took to convert bird flu - which can kill more than half of those infected but does not spread easily - into a highly-contagious virus. They said this knowledge would be vital for the development of vaccines and drugs to prevent a possible pandemic.
But others argue the virus should never have been created - and warn the potential for the bug to escape from the lab is "staggering". There are also fears the recipe will be seized on by terrorists looking for a biological weapon.
The US government is so concerned that its advisers are trying to block the details of the virus's manufacture from being published.
National Science Advisory Board for Biosecurity chairman Paul Kiem, an anthrax expert, said: "I can't think of another pathogenic organism that is as scary as this one. I don't think anthrax is scary at all compared to this."
However, others pointed out that similar fears - raised six years ago when another team of scientists recreated the Spanish flu virus that killed up 50million in 1918 - proved groundless. The latest controversy surrounds the H5N1 bird flu virus. In 2005, there were warnings of a potential bird flu global pandemic which would kill hundreds of millions.
Of the 573 people that have caught the bug so far worldwide, 336 have died. However, the germ's inability to spread easily from person to person means the predicted pandemic has never materialised.
Now, scientists at the Erasmus Medical Centre in Rotterdam have created a H5N1 bird flu that spreads as easily as winter flu. In experiments on ferrets - whose flu symptoms are most like humans' - just five mutations in two key genes turned the 'normal' bird flu into a highly contagious, super-spreader.
The scientist behind the project, Ron Fouchier, said: "We now know which mutations to watch for in the case of an outbreak and we can stop the outbreak before it is too late."
A university spokesman said: "If this type of research is carried out under maximum safety conditions, the benefits are greater than the risks."
But Donald Henderson, an expert in biosecurity who spearheaded the worldwide drive to eradicate smallpox, told New Scientist magazine if a highly contagious virus with a 50 per cent kill rate got loose, "a catastrophe would result".
Last night, the journal Science said the U.S. government's request to publish only an abbreviated version of Dr Fouchier's work was being taken very seriously.
- The Daily Mail