No alliance is expected to win a clear majority but Prime Minister Manmohan Singh's coalition was well ahead of an alliance led by the Hindu nationalist opposition, the Bharatiya Janata Party (BJP).

The Congress party-led coalition was projected to win more than 200 of the total 543 parliamentary seats at stake.

To rule, a party or a coalition requires the support of 272 members of parliament.

"So if you want to project from this, it looks like Congress will not only emerge as the single largest party but will be comfortably ahead," Vinod Mehta, editor of Outlook magazine, said.

India's booming economic growth for the past four years, including rising rural incomes, may well have worked for the Congress-led coalition headed by the reformist Singh.

A severe financial downturn that began last year and is continuing in Asia's third largest economy appeared to have had little impact on the fortunes of the ruling alliance.

"It seems to me that we must acknowledge the economy," said political analyst Mahesh Rangarajan. "Despite the slowdown in the economy in the last year, these four or five years have been among the best in India's recorded economic history."

Congress party supporters, their arms in the air and carrying banners of star campaigners Rahul and Priyanka Gandhi, set off firecrackers in celebration in New Delhi on news of the election returns.

"Victory is ours, the writing is on the wall for the BJP and all the other parties that thought they could beat us," said Mukesh Narula, wearing a party flag as a bandana.

Computerized counting of votes at hundreds of centers across the country began at 10:30 p.m. EST with the results for all parliamentary seats due later in the day.

Source: reuters.com India Congress alliance heads for victory in election