'Three dead' in India explosion

Indian authorities say the rebels are the 'biggest threat' to security

Three people were killed when a medical van was blown up by an improvised explosive device in the Indian state of West Bengal, police say.

They have blamed Maoist rebels for triggering the blast.

The explosion occurred in a remote jungle area in West Midnapore district near the village of Chowkisal.

About 6,000 people have been killed in violence linked to Maoist rebels over the past 20 years. They are active in states across east and central India.

Police say that in the latest incident, a doctor and his driver were among those killed.

They say that the Maoists had possibly laid the explosives to target a police convoy but they hit the medical van instead.

The Maoists focus on areas where people are poor but there is great mineral wealth.

The rebels say they represent the rights of landless farmhands and tribal communities.

They have attacked police outposts and enforced strikes in India's mineral heartland.

Indian Prime Minister Manmohan Singh recently said the Maoist movement is the "biggest threat to India's national security".