The rebels set off a powerful landmine under the van of a patrol party, killing nine policemen, senior police officer M.W Ansari told Reuters.

Eight policemen were also wounded in the attack in Dantewada district, 480 km south of Raipur, he said.

In another incident, Maoists raided a police station in Jashpur district, about 450 km north of Raipur, and shot dead three policemen and wounded five, district police chief Purshotam Gautam said.