UPDATE 1-Indian Maoists kill 12 policemen in forest ambush

(Updates with higher toll, details)

RAIPUR, India Oct 20 (Reuters) - Suspected Maoist insurgents killed at least 12 policemen and wounded several others when they opened fire on a patrol in central India on Monday, police said.

A federal police patrol was ambushed in the forests of Bastar in the central state of Chhattisgarh, Girdhari Nayak, the state's anti-Maoist operations chief, told Reuters.

Maoist rebels say they are fighting for the rights of poor farmers and landless labourers and they regularly attack government property and policemen.

In July, 38 policemen of the elite anti-insurgency unit were killed by the rebels in the eastern state of Orissa.

Thousands of people have been killed in the insurgency, which began in the late 1960s and stretches through rural pockets of eastern and central India.

Prime Minister Manmohan Singh has described the insurgency as the gravest threat to India's internal security. (Reporting by Sujeet Kumar; Editing by Bappa Majumdar and Alex Richardson)