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 the western state of Gujarat, election frontrunner Narendra Modi waved to thousands of supporters of his opposition Bharatiya Janata Party (BJP) as he filed his papers to stand in the Vadodara constituency. The BJP is expected to oust the ruling Congress party in the elections for the 543-seat parliament at a time of low economic growth as well as seething anger over corruption and rising food prices. Modi, a hardline Hindu nationalist widely tipped to emerge as prime minister, later mocked the Gandhi family, India’s most famous political dynasty who head Congress.“They go to poor people’s homes, eat their food, snap photos and show (them) to the world. (But) they don’t know what poverty is,” he told a rally.Congress president Sonia Gandhi lashed out at Modi during campaigning, saying he was wrongly being “projected as a cure for all ills and as a magician for the country”.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 (260 miles) 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 told AFP. 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.Security was tight in constituencies in the four small northeastern states close to the disputed border with China. They were part of the second wave of voting in the election, which has been staggered to allow security forces time to redeploy.Voters flocked early to polling stations in Arunachal Pradesh state, an eastern stretch of the Himalayas that China claims as its own, despite pouring rain overnight, the Press Trust of India news agency reported.During campaigning in February in the area, the scene of a 1962 war between India and China, Modi had warned Beijing to shed its “expansionist mindset”.Hundreds of extra security forces have been deployed in neighbouring and underdeveloped Nagaland state - where rebels have long waged a campaign for more rights - for polling day.Nagaland chief minister Neiphiu Rio, who has brought 11 regional parties under one banner for the polls, has promised to support a BJP-led coalition in hopes of bringing peace and development to the northeast.“The Congress party has failed to impress the people in our region in terms of all-round development,” Rio told AFP after casting his vote in a village in the state.Six seats are up for grabs on Wednesday in Arunachal Pradesh, Nagaland, Meghalaya and Manipur, often neglected states in a part of India wedged between China, Bangladesh and Myanmar.A third phase of voting is scheduled for Thursday which will be by far the biggest to date, with constituencies in 14 states including the capital region heading to the ballot box.As well as Vadodara, Modi is also set to stand for a second seat in the northern holy Hindu city of Varanasi on the river Ganges in the battleground state of Uttar Pradesh.