Maoists kill two policemen in central India ambush

RAIPUR, India, April 12 (Reuters) - Maoist militants killed two policemen and a civilian in the central Indian state of Chhattisgarh on Sunday, a senior police officer said, as the rebels stepped up violent attacks ahead of a general election.

Deputy Inspector General Pawan Deo said about 40 armed Maoist rebels ambushed members of the Central Reserve Police Force (CRPF) and local police in a forested area of Bijapur district, some 500 km (310 miles) south of Raipur.

Six Maoist militants were also killed in two separate encounters with the CRPF in the state's restive Bastar region, Deo said.

The Maoists, who say they are fighting for the rights of poor farmers and landless labourers, have called for a boycott of the polls that get underway this week and threatened to chop off the hands of those who cast their votes.

Voters in mineral-rich Chhattisgarh are due to go to the polls on Thursday.

Thousands have been killed in the Maoist insurgency which began in the late 1960s and now stretches throughout rural areas of east, central and southern India.

Prime Minister Manmohan Singh has described the insurgency as one of the gravest threats to India's internal security. (Reporting by Sujeet Kumar; Editing by Rina Chandran and Sophie Hares)