Belgium has banned the movement of all poultry and eggs

The slaughter of about 270,000 birds in the north-eastern border region of Limburg was ordered after more cases were detected at two local farms on Saturday.

The Belgian authorities have already destroyed a quarter of a million birds, following the discovery of the first case in the area on Wednesday.

Fear that the disease may spread to people were heightened on Saturday, when the Dutch authorities said a veterinarian who died earlier in the week may have been the first human victim of the outbreak.

The Dutch Government said it was investigating whether the virus had mutated.

More than 11 million chickens - around 10% of the Dutch chicken population - have been slaughtered since the outbreak of bird flu, or avian influenza, began in February.

Human version

The Belgian authorities said they would begin destroying all poultry within a three-kilometre (2-mile) radius of the farms where new cases were found on Saturday.

Egg exports have come to a standstill

The movement of poultry and eggs from Belgian farms has been halted.

The Belgian government stressed there was no danger from eating poultry or eggs, and said any risk to people came from contact with sick birds.

The World Health Organization said the disease did not appear to spread easily from human to human.

In 1997, six people in Hong Kong died after an outbreak of bird flu crossed into the human population.

All Dutch poultry and egg exports remain banned - costing the industry an estimated two million euros a day.