President George W. Bush's administration said Monday it was "hopeful" the US Congress would endorse the agreement, which would lift a ban on nuclear trade with India after three decades, before his term ends in January.

But lawmakers who began a short final session Monday ahead of a presidential vote on November 4 have sought greater transparency on the deal, especially details of its approval by the Nuclear Supplier Group (NSG) last week.

The greenlight from the NSG, a regulator of sale of nuclear fuel and technology, came after countries such as China, New Zealand, Austria and Ireland expressed reservation about opening up nuclear commerce with India, which is not a member of the nuclear Non Proliferation Treaty (NPT).

"Before we vote, Congress needs to study the NSG decision, along with any agreements that were made behind the scenes to bring it about," said Howard Berman, chairman of the House of Representatives foreign affairs committee.

Berman, who plays an influential role in rallying House support for the deal, has demanded that any final agreement must be consistent with a special law -- the Hyde Act -- passed overwhelmingly in 2006 laying the foundation for the nuclear deal.

A key condition under the law is immediate termination of all nuclear commerce by NSG member states if India detonates a nuclear explosive device.

"If the administration wants to seek special procedures to speed congressional consideration, it will have to show how the NSG decision is consistent with the Hyde Act ..., including which technologies can be sent to India and what impact a nuclear test by India would have," he said.

"The burden of proof is on the Bush Administration so that Congress can be assured that what we're being asked to approve conforms with US law," he said.

The White House said it would work with the Congress to get the deal approved.

"We're hopeful," spokesman Gordon Johndroe said of prospects for the pact, which Bush and Indian Prime Minister Manmohan Singh signed in July 2005.

Johndroe declined to confirm directly that the United States would cut off nuclear fuel supplies if India tested a nuclear weapon.

"India knows what the international reaction to a test will be," he said.

Weapons experts said the NSG did not provide clear restrictions over India's involvement in nuclear trade or about terminating such commerce if India conducted a test explosion.

"It is strongly implied in the waiver (given by the NSG) but it is not explicit as we believe it should have been," Daryl Kimball, executive director of the US Arms Control Association, told AFP.

"I find it hard to understand how any responsible legislator believes that Congress can rush this through ... especially given the many ambiguities and contradictions between the Hyde Act, the 123 (operational) agreement (signed between the United States and India) and the NSG waiver," he said.

Sharon Squassoni, a nuclear expert who once advised the US Congress, said India had not key provisions of the Hyde Act, including filing a declaration with the International Atomic Energy Agency, the UN nuclear watchdog, of the civilian nuclear facilities New Delhi would place under safeguards.

It has also not made "substantial progress" on negotiating an additional protocol with the agency for strengthened safeguard measures, she said.

The Bush admimistration also may not have sufficient time to get the deal through Congress, she added.

US law requires that the Congress be in 30 days of continuous session to consider the deal. Given the targeted date of adjournment of September 26, this would leave only 15 days of continuous session.

"If the political stars are aligned with a tremendous amount of work, they might be able to make it happen but not under (current laws) because it is very doubtful they would have enough time," Squassoni said.