India has ordered chickens to be culled in the eastern state of West Bengal following an outbreak of the bird flu.

The federal government says eggs and chicken feed must also be destroyed in the vicinity of villages where poultry samples tested positive for the H5 strain of the avian influenza.

Last month, the United Nations Food and Agriculture Organization warned of a possible resurgence of the deadly bird flu virus, including a mutant strain that is spreading in Asia and elsewhere.

It was not immediately clear whether the latest outbreak in India is related to the new Asian strain, which appears able to bypass the defenses provided by existing vaccines.

West Bengal has been hit by bird flu outbreaks in the past.