Voting has closed in India's general elections, with exit polls predicting that the Hindu nationalist Narendra Modi is on course to become the country's new prime minister.

Four major exit polls on Monday suggested that the Modi-led opposition Bharatiya Janata Party (BJP) and its allies were set to sweep to a parliamentary majority in an election that saw 551 million people turn out to vote.

According to a poll conducted by research group CSDS, the BJP-led alliance was forecast to win between 270-282 seats. Another poll, by Today's Chanakya , showed the BJP emerging with enough seats to rule on its own.

Modi's BJP and its allies need 272 seats to form a government.

Strong momentum

The BJP went into this year's election with strong momentum on promises of economic growth.

The ruling Congress-led coalition, in power for the last 10 years, has had its standing severely dented by a string of corruption scandals. The Congress has governed the country for more than 50 years since freedom from British rule in 1947.

The Congress tally is forecast to slump with the research group CSDS giving just 92-102 seats for the coalition.

However, with results of the elections due on May 16, predicting the polls is notoriously difficult.

In 2004 and 2009, national exit polls falsely predicted that the BJP would win. On both occasions, the Congress went on to form governing coalitions.

"We will only know if this 'Modi wave' has really happened after the election results," said Praveen Rai, a political analyst at CSDS. "It still might be more of a media wave, a manufactured wave."

Uttar Pradesh, India's most populous state and a crucial political battleground, is particularly tricky for pollsters to forecast because it is a caste-sensitive state where some voters are afraid to speak frankly about who they chose, said Rai.