Section 105(8) in the Senate version of the bill originally required a determination by the president that India is fully and actively participating in US and international efforts to dissuade, sanction and contain Iran for its nuclear programme consistent with United Nations Security Council resolutions.

Section 106 prohibited the export of any equipment, materials or technology related to the enrichment of uranium, the processing of spent fuel, or the production of heavy water, while Section 107 required an end-use monitoring programme to be carried out with respect to US exports and re-exports of nuclear materials, equipment and technology sold or leased to India.

But with no voting scheduled on the final piece of legislation by late Thursday night "it's coming down to the wire" is how State Department spokesperson Sean McCormack put it.

Asked if US under secretary of state for political affairs, R. Nicholas Burns, who is Washington's chief negotiator for the India deal, was in New Delhi because India may have a problem with some provisions of the emerging legislation, he replied, "Not as far as I know."

"You know that this can be a nerve-wracking process as you go through this. But this is how democracies work. The Indian government understands that and we're sure that they appreciate it.