Veterinary workers culled poultry in India's famous tea-growing hills of Darjeeling on Wednesday after a fresh H5N1 bird flu outbreak, officials said.

Veterinary and health workers scoured the verdant Himalayan region looking for dead chickens and ducks and planned to cull at least 7,000 birds in the next 24 hours.

Poultry products had been banned in Darjeeling town, popular with tourists.

"Dead bird samples from backyard poultry tested positive for H5N1 in the Rangli Rangliot area of Darjeeling hills on Wednesday," Surendra Gupta, a senior government official, told Reuters.

Bird flu first broke out in India in 2006. Millions of chicken and ducks have been culled since then to contain the virus, but it has resurfaced from time to time. India has reported no human infections.

The latest outbreak of the virus in poultry is the fourth in the state of West Bengal since 2007.

More than 4 million birds were culled in the state early last year in what the World Health Organisation (WHO) described as India's worst-ever bird flu outbreak.

Hundreds of thousands of birds were also culled in India's northeast after bird flu was detected in two states in November.

On Wednesday, experts rushed to the northeastern state of Manipur, which borders Myanmar, after villagers said nearly 100 birds had suddenly died and a dozen villagers had fallen sick.

Blood samples of the villagers were being tested.

Experts have warned the H5N1 virus might mutate or combine with the highly contagious seasonal influenza virus and spark a pandemic that could kill millions of people across the world.

According to the World Health Organization, H5N1 bird flu has infected more than 390 people in 15 countries and killed at least 247 of them since the virus resurfaced in Asia in 2003.