Bird flu [Images] appeared right at the doorstep of Kolkata on Friday with two more districts of West Bengal, Purulia and Howrah, falling prey to the deadly virus that has now spread to more than half of the state.

Expert teams were accompanied by police force at many places in culling operations in view of resentment among many villagers fearing loss of livelihood.

The High Security Animal Disease Laboratory in Bhopal on Friday confirmed avian influenza (H5) in samples from Sankrail block of Howrah district and Santuri block of Purulia district, an official statement in Delhi said.

The virus has now spread to more than half of the state's 19 districts.  The 11 districts affected by bird flu are Birbhum, South Dinajpur, Murshidabad, Nadia, Burdwan, Bankura, Malda, Coochbehar and Hooghly, Purulia and Howrah.

The samples from Mayureswar-II and Khoyrasole blocks of Birbhum district and Kandi block of Murshidabad district have also tested positive for avian influenza, it said.

Official sources in Kolkata said at least 10 lakh chicken have been culled in the nine affected districts while 1.46 lakh eggs have been destroyed till January 24.

At least 901 rapid response teams were deployed on Friday in the state for carrying out culling and surveillance operations.

Confirming the deadly H5N1 virus in Purulia, District Magistrate Deepak Ranjan Kar said the avian flu surfaced at Ramchandrapur village under Santuri block in the district.

Elsewhere in the state, expert teams had to seek help from police force at many places in culling operations. The force was sought to thwart any untoward incident, particularly in view of resentment among many villagers fearing loss of livelihood, Coochbehar District Magistrate Rajesh Sinha said.