The culling of birds began on Tuesday in West Bengal's Nadia district after the union health ministry confirmed that samples had tested positive for bird flu, an official said.
"We have started culling within a three-kilometre radius of Tehatta Block 1. We have taken other preventive measures within 10-km radius," said A.K. Agarwal, secretary, department of Animal Resources, West Bengal.
Agrawal said that on September 14, 849 birds died. Their samples were sent to a lab in Kolkata.
"After the test came positive we again went for a testing in a lab in Bhopal which confirmed it as bird flu. So now we have started the process of culling. There are around 51,000 birds in a three-kilometer radius."
The samples forwarded to the Eastern Region Disease Diagnostic Laboratory (ERDDL) in Kolkata and High Security Animal Disease Laboratory (HSADL) in Bhopal tested positive for H5 strain of Avian Influenza, the labs said.
"It has been decided to immediately commence the culling of birds and destruction of eggs and feed material to control further spread of the disease. The virus has been contained in the affected area," it added.
The central government has advised the state to ban movement of poultry and poultry products in the infected area and to close poultry and egg markets and shops within a radius of 10 kms from the infected site.
They have suggested a ban on the movement of farm personnel, restricting access to wild and stray birds and stopping access to infected premises.
As regards compensation for loss of poultry on account of culling and destruction of birds, the central government will share costs on a 50:50 basis with the state, the statement said.
The last outbreak took place during February-March in Tripura. The country was declared free from the disease on July 4.