Suspected Maoist rebels killed 12 paramilitary commandos on Monday in a remote part of central India, a police official said, the latest attack in the country's simmering internal conflict.
The soldiers were guarding road workers in the Sukma district of Chhattisgargh state, a hotbed of insurgent violence, when they came under fire.
"So far, we know that 12 CRPF (Central Reserve Police Force) personnel have been martyred in the Maoist attack," Bhagwati Singh, a police spokesman, told AFP by telephone.
"Our teams have been deployed there. We will receive more information about the situation soon."
Singh could not confirm reports in local media that at least six commandos had been critically injured and were being airlifted to safety.
The attack is the latest in a long-running conflict between insurgents and Indian authorities in the forests and rural areas of mainly central and eastern India.
Last month Maoist rebels killed 11 paramilitary policemen in the same state after ambushing their convoy.
The guerrillas, who say they are fighting for the rights of tribal people and landless farmers, often collect funds through extortion.
The Maoists are believed to be present in at least 20 states but are most active in Chhattisgarh, Orissa, Bihar, Jharkhand and Maharashtra.
The decades-long insurgency is believed to have cost tens of thousands of lives, with much action focused around the insurgent-dominated "Red Corridor" stretching through central and eastern India.
Critics believe attempts to end the revolt through tough security offensives are doomed to fail, saying the real solution is better governance and development of the region.