Hundreds of leftists vowed to paralyse the airports of Calcutta, Bagdogra and Kalaikunda.

"We will lay siege to Kalaikunda, where the exercises take place," said Anil Biswas, state organisation chief of the Communist Party of India (Marxist) that leads West Bengal's ruling leftist coalition.

"We are against air exercises with the United States. Such a move will also jeopardise our national security. Millions will rise in protests."

The BBC's Subir Bhaumik in Calcutta says the US air force will be flying in F-16 fighters from Misawa in Japan and the Indians will use fighters of both Russian and Western origin for the exercises, called "Cope India".

Indian Defence Minister Pranab Mukherjee said the exercises would go ahead without interruption.