Cooch Behar and Hoogly were on Wednesday declared bird flu hit, taking the number of affected districts in the state to nine even as authorities set a target of culling 3 lakh chicken daily.
"Samples of chicken sent from Cooch Behar and Hooghly districts to the Highrisk Security Disease Laboratory in Bhopal on Tuesday tested positive," Animal Resources Development Minister Anisur Rahaman told PTI on Wednesday.
"We have been informed by the Centre. Steps will be taken accordingly," he said.
"Steps are being taken to officially notify both Cooch Behar and Hooghly districts bird flu affected, for the next course of action including culling," Rahaman said.
The samples which tested positive were from Dinhata in Cooch Behar district and Balagarh in Hooghly district, he said.
There was, however, no case of humans beings being affected, the minister said.
The target of culling which was set at 20 lakh was also likely to increase, he said.
The daily target now was 3 lakh with 600 teams on the job from Wednesday, he said.
About 150 technical teams from eight states, including Haryana, Assam, Maharashtra, Orissa and Jharkhand would soon join to monitor the culling.
West Bengal's border with neighbouring states has already been sealed, the minister said.
In the already affected districts, the H5N1 virus was reported from more blocks in Nadia and Murshidabad districts.
Nadia District Magistrate Omkar Singh Meena said the virus spread to Haringhata and Nakhashipara blocks. An action plan was being prepared for these two areas. Culling was on in the other affected areas.
In Murshidabad district, the disease spread to Galsir-1 block, district officials said. Eight other blocks have already been affected.
In Malda, declared affected on Tuesday, culling could not start on Wednesday because of shortage of staff, Deputy Director of Animal Resource Development department, N K Shit said.
In Burdwan district, due to a dispute between the administrations of Kalna and Katwa, no action has taken so far to control the disease in eight villages under Purbastahli block.
Burdwan District Magistrate Subir Chatterjee had to intervene and ask the Katwa administration to begin culling from Wednesday.
Meanwhile, about 700 chickens died in Bardhaman town on Tuesday night.
While a Central team arrived in Birbhum district on Tuesday morning, death of chickens was reported from Howrah district, which is unaffected so far. The district borders Kolkata.
In Cooch Behar district, the district's animal resources department sources said deaths of chickens were reported at Khalisamari of Mathabhanga-I block.
ARD sources in the district said that bird deaths were reported from four blocks out of 12. These were Dinhata-I, Cooch Behar-I, Mathabhanga-I and Mekhliganj.
In Haribhanga of Cooch Behar-I, carcasses of 10 migratory birds were found on Tuesday. The samples were sent to Kolkata.