The ministry's bird flu screening system, in which state hospitals and other health care facilities screen their patients, might not cover blue-collar workers used to buying drugs at pharmacies instead of visiting doctors, said caretaker Public Health Minister Pinij Charusombat.

There were fast-spreading rainy-season diseases - the common flu, dengue and enterovirus 71 - which needed special attention, said the minister.

Customers coming in with flu-like symptoms could be asked by the drug stores if they had been exposed to sources of the bird-flu virus, said Pinij.

In another development, about 80 poultry farms have been barred from raising chickens for three months by the authorities.

Many farmers fear there have also expressed reservations that the 75 per cent financial compensation they had been offered to switch to a close-system farm would not be enough to cover the cost of setting up one.