NEW DELHI -- Millions of Indian voters wrapped up the country's mammoth national election Monday, braving the searing sun on the final day of polling in which a Hindu nationalist opposition candidate is seen as the front-runner for prime minister.

With 814 million eligible voters, India has been voting in phases over six weeks, with results expected Friday.

The main Hindu opposition Bharatiya Janata Party went into the election with strong momentum on promises of economic growth. Early polls suggest there is deep dissatisfaction with the governing Congress party's 10 years in power.

Exit polls, which in India are notorious for being inaccurate, are expected Monday night after the final round of voting ends.

Thousands lined up early Monday to vote in the revered Hindu holy city of Varanasi, where Narendra Modi, the main BJP candidate for prime minister, is seeking election. The temperature was expected to soar to 42 degrees Celsius (107 Fahrenheit).

Modi is locked in a battle with Arvind Kejriwal, the chief of India's anti-corruption party, and Ajay Rai of the Congress party.

"We want to vote for a candidate who is accessible, someone we can go to when we have problems, someone who can come and help us when we are in need," said Sofia Shaheen, a school teacher.

Girija Shankar, a retired government officer, said he was looking for a clean government. "We should only support a person who can deliver this to us."

A clash erupted as the voting opened in West Bengal state, where Ajay Dasgupta, a Communist Party of India (Marxist) spokesman, accused governing Trinamool Congress workers of firing at his party supporters, wounding four of them.

The clash was reported in a village 35 kilometres (20 miles) northeast of Calcutta, the state capital. The Trinamool Congress party denied the charge.

A recent poll by the Pew Research Center said 63 per cent of Indians prefer the BJP over the incumbent Congress Party.

Modi's chief rival is Rahul Gandhi, the 43-year-old vice-president of Congress and scion of the Gandhi family.

Indians turned out in large numbers to vote, with the Election Commission saying the turnout percentage over the six weeks in 502 parliamentary constituencies until May 8 was 66.27 per cent, up from 58.13 per cent in 2009 elections.

Elections in India are generally considered free and fair, with even the powerful often falling to defeat. But there are also challenges, with age-old traditions of caste loyalty, patriarchy and nepotism often influencing voting patterns.

This year's election was bitterly fought, and often marred by religious divisions and personal attacks.

The BJP's carefully crafted and well-financed campaign promises good governance at a time when the ruling Congress party has been plagued by repeated scandals, and its leader Rahul Gandhi has generally failed to inspire the public, leaving many analysts to predict that the BJP will likely emerge with the largest number of seats.