Crisis talks between India's ruling Congress party and its left-wing allies ended Wednesday without them resolving a dispute over a nuclear energy deal with the United States, officials said.

The parties, however, agreed to meet "in due course" for more negotiations over the pact with Washington, a divisive accord that has threatened to bring down the government and send India into early elections.

Foreign Minister Pranab Mukherjee told reporters the government coalition partners discussed "all aspects" of the deal, which would open India to long-denied Western nuclear energy technology.

Mukherjee, who led the 90-minute meeting between his Congress party and its anti-American communist partners, who are fiercely opposed to the deal, said the two sides will hold further talks.

"The next meeting of the committee to be convened in due course will finalise its findings," he told reporters, declining to reply to questions.

Congress party sources said the next round of the deadlocked talks were likely after a gap of at least 10 days to allow the powerful Marxists to hold their own separate conclave on the thorny deal on Sunday.

India, a declared nuclear weapons power that refuses to sign the Non-Proliferation Treaty (NPT), is currently barred from buying atomic energy technology.

But the pact with the United States would bypass that by allowing India to shop for such hardware and fuel if it can separate its civil and military nuclear programmes and allow some United Nations inspections.

India must work out a safeguards agreement with the International Atomic Energy Agency and get a waiver from the 45-nation Nuclear Suppliers Group.

The agreement then would return to the US Congress for ratification. New Delhi is aiming to get the deal there before US President George W. Bush leaves office in January 2009.

India's communists on the other hand have vowed to force early elections if the government forges ahead with implementing the deal.

"At the moment, we oppose the deal in its present form," Communist Party of India leader Doraiswamy Raja told AFP, signalling the unbending stance of the communists who have 59 MPs in India's 543-member parliament.

Congress, which swept to power in 2004, has 153 MPs and desperately needs the backing of the communists to last its full five-year term in office until May 2009.

It is unclear if Congress is ready to test the communists and try and push through the deal, which was signed in 2005, or face an electorate unhappy with double-digit inflation.

Prime Minister Manmohan Singh said the deal was crucial for India to continue fuelling economic growth. The country imports 70 percent of its crude oil needs and badly requires alternative sources of energy -- including new atomic reactors.

But leftist leaders said the benefits of the deal have been exaggerated, and they have opposed entering the traditionally non-aligned India into a strategic pact with Washington.