Over a million birds were slaughtered last year

Dozens of health workers dressed in white surgical gowns arrived at the farms on Saturday to destroy and hygienically dispose of the birds.

The virus is believed to have already killed more than 200 chickens at the infected farms.

But it is different from the H5N1 strain that killed six people in 1997, and a government spokeswoman said: "So far there is no indication to show that this strain will endanger humans".

Vaccination programme

The government has also launched a vaccination programme which is due to start next week.

Approximately 400,000 birds in 21 other poultry farms in the same district will be inoculated against the disease.

"We think vaccination will help prevent the virus from further circulating in the area," said Dr Liu Kwei-kin, deputy director of Hong Kong's Department of Agriculture, Fisheries and Conservation.

The recent avian flu outbreaks have prompted strong public criticism of the government.

We can't wipe out the virus - it exists in the environment. But we can prevent it from infecting our farms

Dr Liu Kwei-kin

In 1997 and again last year, the territory's entire chicken population of over one million birds was slaughtered.

About 860,000 birds were killed in the latest outbreak this February.

"We can't wipe out the virus - it exists in the environment. But we can prevent it from infecting our farms," said Dr Liu.

He also assured Hong Kong consumers that chickens injected with the vaccine were safe to eat.

"The vaccine is not dangerous to humans and is safe for (human) consumption. It should not affect the taste of chicken nor the texture," he said.