NEW DELHI: Maoist rebels killed three soldiers guarding polling officials in central India on Wednesday, highlighting security concerns in the world's biggest elections as the second phase of voting got under way.

The rebels staged the attack in Chhattisgarh state in the country's insurgency-racked centre one day before polling is held there, as voters in the restive northeast of the country cast their ballots.

In Chhattisgarh, police said rebels attacked a convoy of paramilitary commandos as they were returning from escorting election officials to a polling station, 415 kilometres south of the state capital Raipur.

“In a gunbattle with the Maoists, three commandos of the central paramilitary forces were killed in the Chintagufa area,” chief of the state's anti-Maoist operations Rajinder Kumar Vij said. Three soldiers were injured.

The deaths underscored the security challenges facing election organisers in India. Separatist and Maoist insurgencies afflict large parts of the northeast, northwest and forested central areas.

Another three soldiers were injured elsewhere in Chhattisgarh when they stepped on a mine laid by rebels, who have been waging a decades-long campaign for greater land and other rights for tribal groups, Vij said.—AFP