The deadly H5N1 bird flu virus has been found in dead poultry and wild birds in India´s northeastern state of Sikkim, which borders China and Nepal, and authorities plan to start culling poultry soon, an official said on Tuesday.

Officials will initially cull an estimated 15,000 chickens and ducks after samples of more than 30 dead birds from Ravangla area in the southern part of the mountainous state tested positive in a federal laboratory.

The affected area borders West Bengal state, which has been grappling with intermittent outbreaks of the virus since 2007.

"Bird flu has been confirmed in Sikkim and we are waiting for the central team of experts to come here," said K.C. Bhutia, a senior veterinary official in the state capital, Gangtok.

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

Hundreds of thousands of birds were culled in India´s northeast after the virus was detected in two states in November.

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

There have been 249 human deaths globally from the H5N1 strain and 397 confirmed cases of infection since the virus resurfaced in Asia in 2003, according to data from the World Health Organisation (WHO).

The WHO described a January 2008 outbreak of bird flu in West Bengal state, when more than 4 million birds were culled, as the worst ever in India.