The conference agreement will help solidify New Delhi's commitments to implement strong export controls, separate its civilian nuclear infrastructure from its weapons programme, and place additional civilian facilities under International Atomic Energy Agency (IAEA) safeguards.

An agreement for peaceful nuclear cooperation with India would be a powerful incentive for India to cooperate closely with the United States in halting proliferation and abstaining from additional tests of nuclear weapons, they said.

In addressing India's concerns over the Iran issue, the conference changed the provision making the deal contingent on New Delhi aligning its Iran policy with that of Washington from a condition to an "expectation".

"The conferees, along with both Houses, place great emphasis on their expectation that India's full cooperation with efforts by the US and the international community to prevent Iran from acquiring the capability to produce nuclear weapons will be forthcoming," the report said.

There was no official word on what had held up the legislation, but reports suggested that House Republican Majority leader John Boehner, one of nine conferees, wanted an unrelated clause to increase India's H1-B visa quota to piggy ride on the bill.