New Delhi: The government on Thursday announced that the country is free of bird flu disease, but continues to keep a watchful eye on vulnerable areas.

Bird flu, also known as avian influenza, is a flu that affects birds. The virus that causes the bird infection can mutate to affect humans.

"The declaration was made here on December 29, 2011, and notified to the World Organisation for Animal Health (OIE)," an official statement said.

There has been no outbreak of the disease after the final disinfection process was completed on September 29, 2011, it said.

"Surveillance around the area of the outbreak since completion of the operation (including culling disinfection and clean up) and surveillance in the rest of the country has shown no evidence of the presence of bird flu (H5N1)," the government said.

A bird flu outbreak was notified on September 8 and 19 last year in Dhubri district of Assam and Nadia district of West Bengal, respectively.

It said it will continue the surveillance work throughout the country, especially in vulnerable areas bordering affected countries.

The Agriculture Ministry has advised state governments to maintain a vigil against the disease, it added.

(Agencies)