Bhubaneswar, (PTI): Twenty-two migratory birds have died in the Chilika lake, the lone brackish water lagoon in Asia, and their samples have been sent to a laboratory in Bhopal to ascertain if they had the deadly birdflu disease.

"Though there was no symptom of flu in the dead birds, we had collected blood sample for laboratory testing," Chilika Divisional Forest Officer, Abhimanyu Behera, told PTI.

The sample would be sent to the High Security Animal Husbandry Laboratory in Bhopal to ascertain the reason behind death of the birds, he said.

Behera said though bird flu spread in other parts of the country, the Chilika lake had not been affected. "Last year also, we had sent blood samples of some birds. Those tested negative to H5N1 virus," he said.

Sources said the officials had so far detected death of only 22 migratory birds.

With the Centre confirming birdflu in neighbouring West Bengal, the Orissa government on Tuesday ordered constant monitoring of migratory birds visiting the Chilika lake.

The Lake authorities had set up two rescue centres to treat the sick avian guests. Besides, officials including rangers, had also been trained how to handle sick birds.

The officials had been provided with protective kits including gloves while dealing with the sick birds.