Bird flu crisis is likely to last several years inflicting "tremendous damage" to bird population, domestic poultry in particular, with continuing threat of the possibility of its turning into human pandemic affecting millions, the UN food agency has warned.

Giving the new assessment, the Food and Agriculture Organization upped its monetary estimates for progressive control of the avian influenza to USD 308 million over the next three years, more than twice the amount it estimated only a few months ago.

To date, FAO has received only 71 million dollars.

The knock-on effect on the poultry sector is enormous and it could deal a significant blow to local, national and regional economies, it said, decrying the fact that international interest is focused almost exclusively on the possibility of bird flu infecting humans to the neglect of its potentially devastating impact on animals.

This fails to recognize that the best way to protect people is to control and try to eradicate the disease in animals, it says.

So far, well over 200 million birds have died or been culled to prevent the disease from spreading since the current outbreak started in South-East Asia in December, 2003.

There have so far been 217 human cases, 123 of them fatal, ascribed to contact with infected birds, but experts fear the virus could mutate, gaining the ability to pass from person to person and, in a worst case scenario, unleashing a deadly human pandemic with the potential to kill millions.