KOLKATA, India (AFP) - Health officials in eastern India began the slaughter of tens of thousands of chickens Wednesday, a day after New Delhi confirmed an outbreak of the deadly avian flu in the region.

Anisur Rahaman, animal resources minister of West Bengal state, told AFP that 55 rapid response teams had fanned out from "core areas like Margram where the disease was first detected," intending to kill more than 400,000 chickens.

The slaughter started a day after India's agriculture ministry confirmed poultry deaths due to avian flu last week in densely-populated West Bengal, which borders Bangladesh, where authorities have struggled to contain an outbreak of the virus.

The birds slaughtered Wednesday were being put into sacks and would be buried, a health official told AFP at Margram village, 125 kilometres (75 miles) from the state capital Kolkata.

But villagers in Margram said they had sold sick and dead birds for human consumption.

"Most of the chickens (in Margram) died in the past fortnight," Mohammed Jinnah, a resident of Margram village, told an AFP photographer. "People here sold the dead chickens as meat for 10 rupees (25 cents) a kilo (2.2 pounds)."

"There are very few chickens left, most of the birds killed by the officers are ducks," he added.

New Delhi said 35,525 poultry in West Bengal's Birbhum district as well as 288 birds in a state-run poultry farm in the state's Dinajpur district had died, but added the outbreak appeared to be localised.

"We have asked the officials to trace all backyard poultry and cull the chickens immediately to stop the spread of the bird flu," Rahaman said.

It was the third outbreak of avian flu in India, home to 1.1 billion people, since 2006.

An isolation centre had been opened in a hospital near the affected area and 300 health workers had been sent with medicines and protective gear, Rahaman said.

Humans are typically infected by coming into direct contact with infected poultry, but experts fear the deadly virus may mutate into a form easily transmissible between humans.

Wild migratory birds have been blamed for the global spread of the disease, which has killed more than 200 people worldwide since 2003.