NEW DELHI - As cases of bird flu increase in parts of the southern Indian state of Kerala, authorities in the adjacent Tamil Nadu state have stepped up surveillance along border districts to prevent the disease from spreading, officials said Thursday.

An alert has been sounded in Tamil Nadu's Nilgiris and Coimbatore districts, which share a long and porous boundary with Kerala.

Transportation of live poultry and eggs from Kerala has been banned.

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Meanwhile, special surveillance teams have been deployed at eight check posts along the Kerala border and one along the Karnataka border.

Poultry farm owners have also been advised to mandatorily carry out disinfection of farm tools and equipment at least twice a month.

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Last week, a bird flu outbreak was reported mainly in the state of Kerala. Around 30,000 birds have been culled in affected areas to prevent the spread of the disease.