BHUBANESWAR - Maoist guerrillas killed five policemen in eastern India on Monday by blowing up their vehicle, police said, in the latest of a spate of attacks that has left 13 dead since Saturday.

Maoists detonated an improvised explosive device under the vehicle close to a new police camp in a remote area of Chhattisgarh state, senior police official RK Vij said. The injured men were airlifted out but one died on the journey and four in hospital, he said.

Maoists killed seven police officers during an exchange of fire in another part of Chhattisgarh state on Saturday. Up to 20 rebels were killed in the battle, Vij said. A member of India’s border security force died on Sunday when rebels opened fire on a nighttime patrol, the police official said.

All the attacks took place in resource-rich Chhattisgarh, one of India’s poorest regions and the site of a major security operation to flush the rebels out of their bases.

The Maoists seek the violent overthrow of the Indian state and have fought authorities for decades, particularly in rural areas of central and eastern India where they enjoy some support. They say they are fighting to give poor farmers and landless labourers control over their land and a greater claim on mineral wealth exploited by mining companies. The number of attacks has fallen in recent years, but security experts say the insurgency remains India’s biggest internal security challenge.

According to AFP: The Maoists are believed to be present in at least 20 states, but are most active in Chhattisgarh, Orissa, Bihar, Jharkhand and Maharashtra, occupying thousands of square kilometres (miles) of land. The insurgency is believed to have cost tens of thousands of lives, with much action focused around the insurgent-dominated, so-called “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. Monday’s attack saw the insurgents use large amounts of explosives to trigger the blast, police said.

“The blast was really powerful,” district police chief Kamal Lochan Kashyap told AFP via telephone from the blast site.