A number of countries, including European Union members, have slapped a ban on the import of live birds and feathers in a desperate attempt to contain the spread of the virus.

"As long as there is a demand, there will be a trade and you can't stamp out illegal trade by banning the legal trade," David Morgan, head of the Scientific Support Unit of the Convention on International Trade in Endangered Species (CITES).

"You just send it further underground, where it becomes more difficult to detect, and you only need one specimen to get through the net to spread the disease."

Around 1.5 million live wild birds are traded internationallly, most of which are parrots and finches originating mainly in South America, Africa and Southeast Asia and being traded to consumers mainly in European Union.

"CITES is opposed to a general unfocused ban on trade," Morgan told journalists. "There are international norms and quarantine standards both at the import and export end and we would like to see these rigorously enforced."

CITES is a convention concluded under the aegis of the United Nations Environment Programme (ENEP) and brings together 169 countries who regulate trade in 30,000 species of wild animals and plants, including 1,500 species of birds.

Last week, the EU extended a ban on imports of live birds from outside the bloc for a further two months. The ban, which covered live birds other than poultry imported for commercial purposes, was imposed in late October.

"I think it is appropriate that we have just extended the ban," a British environment minister, Jim Knight, told journalists.