7 August 2012 Last updated at 03:38 ET

India: 'Maoist' landmine attacks kill three policemen

India's PM has described the Maoists as the biggest internal security threat

At least three policemen have been killed and six others injured in two separate attacks by suspected Maoist rebels in India's Chhattisgarh state.

The men were killed when their vehicles were hit by landmines in the adjoining Dantewada and Bijapur districts.

Maoists, who are active in the region, say they are fighting for the rights of tribals and landless poor.

One of the attacks targeted a police unit guarding a road construction site, officials said.

The road in Dantewada is being built with central government funds but because of the frequent attacks by the Maoists, the construction crews have "abandoned many of these development projects", district collector Om Prakash Choudhury said.

The areas where the Maoists are most active are some of the least developed in the country and in desperate need of infrastructure.

In rebel-dominated Bijapur district, rights activist said last month that police shot and killed 17 "innocent villagers" claiming they were Maoists.

India's prime minister has described the Maoist insurgency as the country's biggest internal security challenge.