Suspected Maoist rebels have killed nine policemen in an attack in eastern India as hundreds of soldiers mobilised to confront the guerrillas in a neighbouring state.

The policemen were travelling in a jeep near Narayanpatna village in Orissa state to clear roads blocked by the rebels earlier when a landmine exploded killing everyone onboard, the local police chief said.

Hundreds of soldiers have been sent to neighbouring West Bengal state where Maoist rebels have captured more than a dozen villages, killed political rivals and burned government property.

However, the progress of the forces into rebel-held territory had been slow since villagers supporting the Maoists had blocked the roads, police said.

Armed confrontation

Earlier this week, a large group of armed rebels entered the Lalgarh region, a heavily forested part of West Bengal, and seized control of many villages. They are believed to have killed at least five members of the Communist Party of India (Marxist), which rules the state.

The rebels, also known as Naxalites after Naxalbari, a village in West Bengal where the movement originated in 1967, say they are insipred by Mao Zedong, China's revolutionary leader.

West Bengal's government has vowed to regain control of the region.

"We can't go for a crackdown right away, as Maoists will use tribal women and children as human shields." Buddhadeb Bhattacharjee, the state's chief minister said. "We have to minimise casualties."

The Naxalites have fought for several decades across India, demanding land and jobs for the poor. They have urged the government not to try to retake the Lalgarh region, warning that local support was on the side of the rebels.