The partly UK-funded research successfully used antibodies from survivors of the virus to stop the full-blown disease from developing in mice.

Results from the study, published in the open access journal PLoS Medicine, could hold the key to finding future treatments for the virus.

The H5N1 strain has killed millions of birds across the globe and has occasionally been passed on to humans with often fatal results.

By mid-May, according to the World Health Organisation, there had been 306 known cases in humans, 185 of them fatal.

But the scientists based in Vietnam, Switzerland and the US, are optimistic that antibodies from Vietnamese survivors could be used in the fight against infection.

The researchers found the antibodies provided significant immunity to mice that were subsequently infected with the Vietnam strain of H5N1.

It significantly cut the amount of virus found in the lungs and almost completely prevented the virus reaching the brain or spleen.

The research was fast-tracked for funding by the UK's Wellcome Trust and was also supported by grants from bodies in the US and Switzerland.

Dr Cameron Simmons, a Wellcome Trust scientist at the Oxford University Clinical Research Unit in Vietnam, said: "We have shown that this technique can work to prevent and neutralise infection by the H5N1 'bird flu' virus in mice.