Dhaka (PTI): Livestock authorities in Bangladesh began culling around 1.6 lakh chickens at a major poultry farm in the capital after the detection of bird flu, which has spread to 42 of the country's 64 administrative districts since its detection in March last year, officials said on Sunday.

Officials said they would need at least two days to cull the entire flock in the farm.

"This would be the highest number of poultry birds to be culled at a single farm since the outbreak of the avian influenza," chief livestock officer Dr Salahuddin Khan told PTI.

So far, more than six lakh chickens have been culled in various affected areas of the country, he said.

Wearing safety robes, livestock workers started culling chickens at the automated Omega Poultry Farm Limited at Badda area of Dhaka late yesterday. Staff first suspected bird flu infection on February 10 when 20 chickens suddenly died.

"It alarmed us all because, usually, no more than one or two chickens die a day. And the number of deaths doubled a couple of days later," the farm's owner Alif Ahmed Khan said.

Salahuddin Khan, however, said the outbreak of the disease appeared to be lessening in the country with officials reporting only one case of avian influenza from the southeastern port city of Chittagong, while "previously we used to receive five to six such cases everyday".