Officials have sent dead poultry from a new area in the worst-hit Birbhum district and adjoining villages in Murshidabad district to confirm if these had been infected with the deadly H5N1 strain of the flu virus.

"The new areas are Khargram in Murshidabad and two blocks and Rampurhat municipality area of Birbhum," West Bengal Animal Resources Development Minister Anisur Rahman said.

The culling was halted for some time at Margram, the worst hit area, after government health workers, affiliated to a ruling Communist Party of India-Marxist (CPI-M) employees' union, alleged that policemen had assaulted one of their leaders, a local television channel reported.

Later Birbhum superintendent of police K.L. Meena told IANS that the agitation had been withdrawn and culling resumed.

"The dispute has been resolved and the health workers have joined work," he said.

Anisur Rahman told IANS Thursday morning that 8,000 birds had been culled in Birbhum district since the operation started Wednesday, and 10,000 in Balurghat area of South Dinajpur district.

"The process is sluggish because the teams are not going to big farms but visiting homes and killing backyard poultry. We are beefing up the operation today," Rahman added.

The three districts now affected are Birbhum, South Dinajpur and Murshidabad.

However, officials have not yet confirmed if the virus in Murshidabad is of the H5N1 strain. They have sent samples to the High Security Animal Disease Laboratory (HSADL) in Bhopal for confirmation.

As a result, no culling has started in Murshidabad yet. The affected areas in the district adjoin Birbhum.

The bird flu scare has also spread to South 24 Parganas district adjoining Kolkata besides other south Bengal districts like Hooghly, Nadia and Burdwan from where reports of poultry deaths are pouring in.

Culling began Wednesday morning for an estimated 378,000 chickens and ducks as the state's poultry owners urged people not to panic but to treat chickens as complete untouchables.

According to the magistrates of Birbhum and South Dinajpur, the toll of poultry birds from the disease in the two districts rose to 55,000 in the past two weeks.

To carry out the culling, masked men in protective gear appeared like aliens in many areas where awareness about the disease is almost nil.

"We have cooked and eaten our chickens because we heard they would have been killed by the government officials anyway. We have not heard much about the symptoms of the disease," said Lakhu Sheikh of Tentulia village in Rampurhat Block 2 in Birbhum, about 250 km from Kolkata.

Tentulia is one of the villages where people resisted culling Wednesday.

Many villagers are also smuggling out their poultry and hiding them, health workers said.

A central health ministry team, including its additional director general and the joint secretary, is arriving in Kolkata to assess the situation and hold talks with the state health officials, Rahman said.

While in some villages there is resistance, in most areas people brought hens, ducks and eggs and collected compensation slips at the rate of Rs.40 per big hen and duck and Rs.30 each for the smaller ones.

Officials said in Birbhum, about 55 awareness teams were formed to inform people about bird flu and identify sick birds.

Control rooms have been set up in each block of the affected regions under the supervision of the Additional Chief Secretary of West Bengal Kalyan Bagchi and Animal Resource Development Director Dilip Das.

The border with Bangladesh has been sealed in the affected areas, especially in South Dinajpur, which shares a long border with the neighbouring country.

As the news about the deadly avian flu spread, the demand and prices for chickens nose-dived in Kolkata markets.

West Bengal Poultry Welfare Association assistant secretary Najrul Islam told IANS that poultry farm owners would hold a press conference with the animal resources development minister to dispel unfounded apprehensions about the virus.

"We are also taking care so that the infection does not spread any further. We are providing medication and trying to disinfect the poultry farms," Islam said.

West Bengal is the fifth state in the country to have been struck by the H5N1 strain of bird flu since the first outbreak in Maharashtra in February 2006, and in Gujarat, Madhya Pradesh and Manipur.

In Nandurbar district of Maharashtra, about a million birds had to be culled in 2006 after the presence of the H5N1 virus was confirmed.

The virus causes a type of influenza in birds that is highly contagious and can be deadly. It does not usually infect people unless they come in close contact with infected birds or contaminated surfaces.

Avian influenza experts say speed in extinguishing the outbreak is crucial. The state government would need to prevent the movement of poultry out of the affected area, they stressed.