"This situation in Asia is unprecedented in the world," said Bernard Vallat, chief of the World Organisation for Animal Health (OIE), the top watchdog for veterinary health.

"Never in the past have we witnessed an avian virus circulating so quickly in such a large part of the world," he said in a statement as experts from 23 Asia Pacific nations convened for three days of talks.

Vallat said the immediate priority for affected nations was to stop the virus in its tracks by slaughtering infected poultry as well as birds that had come in contact with them.

"This is the best method to control the disease wherever possible, but many issues have to be solved: adequate compensation for farmers, the management of carcass disposal compatible with environmental risks and use of acceptable methods of killing," he said.

World Health Organisation (WHO) representative in Thailand, Bjorn Melgaard, also said bird flu was having an unparallelled impact on the region and that it was clearly not yet under control.

"These outbreaks of H5N1 have been unprecedented in scale and geographical spread. Not only have they threatened human health globally, they have also inflicted significant damage on commercial agriculture and most painfully on individual farmers and their families," he said.