Insurgents 'ambush Indian police'

At least 12 policemen have been killed by Maoists in the central Indian state of Chhattisgarh, officials say.

A national police patrol was ambushed by the insurgents in a forest, the state official in charge of anti-Maoist operations told Reuters news agency.

About 6,000 people have been killed in violence linked to the Maoist rebels in India over the past 20 years.

The Maoists are active in many Indian states and say they represent landless farmhands and tribal communities.

The prime minister has described them as the single biggest threat to India's security.

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