KOLKATA, India, March 28 (Reuters) - Thousands of chickens have been culled in a bid to contain an outbreak of bird flu in India's eastern state of West Bengal which has struggled to control the virus since January.

West Bengal briefly contained the outbreak by culling nearly four million birds in 13 of its 19 districts, but the virus has intermittently resurfaced.

On Friday, officials said the virus had spread to Jalpiguri, the 14th district to be hit by bird flu this year.

The communist-ruled state government said villagers were resisting culling operations.

"We are trying our best to convince villagers to hand over chickens and ducks for culling, but they are hiding the birds inside their homes," Anisur Rahaman, West Bengal's animal resources minister said by telephone.

Health workers said they were also looking for people with flu-like symptoms in Jalpaiguri after hundreds of backyard poultry died in the last few days.

India has so far not reported any human infections. Experts fear the H5N1 strain could mutate into a form easily transmitted from person to person, leading to a pandemic.

Poultry sales in the eastern state had fallen by about 70 percent and traders said they were still struggling to overcome losses. (Reporting by Tamajit Pain; Editing by Bappa Majumdar)

AlertNet news is provided by