NEW DELHI: Rahul Gandhi, frontman for India's ruling Congress party, warned Sunday on the eve of the world's biggest election that the country faces religious turmoil if the opposition Hindu nationalist party wins power.

Gandhi said majority Hindus would be pitted against minority Muslims if hardliner Narendra Modi and his Bharatiya Janata Party (BJP) clinched power, as widely predicted, during the marathon six-week ballot starting on Monday.

“Wherever these people (BJP) go they create fights. They'll pit Hindus and Muslims against each other,” Gandhi told a rally in the town of Sirsa 250 kilometres (155 miles) from New Delhi.

“We walk with everybody, be it Hindus, Muslims, Sikhs, Christians. We walk with people from all communities, castes, religions and regions and that is our politics,” said Gandhi, the 43-year-old scion of India's famous political dynasty.

“We don't do politics of anger and division,” Gandhi said, as he implored voters to back Congress, which looks set for a crushing defeat at the polls after a decade in power.

Voting will begin in the two remote northeastern states of Assam and Tripura, before spreading across the country of 814 million eligible voters in a staggered process. Results are due on May 16.

Modi, a popular but divisive leader tainted by deadly religious riots in 2002, is set to sweep to power on a promise of reviving the country's battered economy and creating jobs.

Modi, the 63-year-old son of a tea seller who rose to become chief minister of the western state of Gujarat, urged voters to give him a strong mandate.

“The problems that have plagued you in the past 60 years, I will get rid of all those problems in just 60 months,” he told thousands of cheering supporters at Bijnor in the battleground state of Uttar Pradesh.

Row over religious tensions

Modi also went on the attack Sunday after a row flared over accusations that his right-hand man stoked tensions against Muslims just days before the election starts.

The campaign, which has largely focused on development, has taken a religious tone in recent days.

Modi accused Congress president and Rahul's mother Sonia Gandhi of failing to deliver on pledges to improve the lives of Muslims, who at 13 per cent of the population are the largest religious minority in Hindu-majority but officially secular India.

“Madam Sonia, nearly 700 (communal) riots happened in the country in one year right under your nose. And 250 of those were in UP (Uttar Pradesh) alone,” he said.

Modi's close aide Amit Shah reportedly told several Hindu leaders to seek “revenge” at the ballot box. He was speaking in a part of Uttar Pradesh hit by Hindu-Muslim violence last year that left some 50 people dead.

“This election is about voting out the government that protects and gives compensation to those who killed Hindus,” Shah reportedly said on Friday.

Congress has asked the Election Commission to order Shah's arrest and ban him from campaigning. A party official accused the BJP of making “horrible”statements and “creating animosity between communities”.

The BJP has said the comments have been taken out of context, but a local Uttar Pradesh magistrate said on Sunday that an investigation was under way into Shah's comments.

Modi has focused on economic reforms throughout the weeks-long elections campaign, largely steering clear of promoting any Hindu nationalist agenda.

But critics accuse him of failing to stop riots in 2002 in Gujarat which he has governed since 2001. The riots there killed more than 1,000 people, mostly Muslims. He has been cleared of any personal wrongdoing.

Opinion polls, fallible in the past and famously wrong when Congress won in 2004, show the BJP likely to emerge as the biggest party in the next 543-member parliament.

Voters, worried about the slowing economy and angry about corruption and high inflation under the Congress-led coalition, appear won over by Modi's pledge to attract investment and overhaul manufacturing.

But the BJP is forecast to fall short of a majority, meaning another coalition will need to be stitched together comprising India's numerous regional parties.

Five seats are up for grabs on Monday in the tea-growing and underdeveloped Assam state, and another one seat in Tripura near the border with Myanmar.

A juice vendor in Assam's Dibrugarh, a Congress stronghold, said he would vote for Modi, as election officials in the town prepared to disperse to polling stations throughout the constituency.

“The Congress has done nothing to control the rising prices. I voted for them in the last two parliamentary elections,” said vendor Motilal Shah.