The trip by Burns, the third ranking official in the US Department of State, is part of the hectic preparations being made by both countries to ensure that President Bush's first visit to India turns out to be a political and diplomatic success just the way Prime Minister Manmohan Singh's [Images] visit to Washington in July last year was.

Official sources here told UNI today that Burns would reach New Delhi on Wednesday after a stopover in Moscow [Images]. He will be joined in the Indian capital by Mumbai-born Ashley Tellis, who joined the State Department recently as an advisor to  Burns on an interim assignment after taking leave for two months from the Carnegie Endowment for International Peace, where he was a senior associate.

Indian Ambassador to the United States Ronen Sen is also leaving here for Delhi this afternoon to participate in the negotiations, the sources said.

The civil nuclear deal was the centre-piece of the India-US Joint Statement issued by Dr Singh and  Bush after their landmark summit here on July 18.

The Indo-US Nuclear Tango

Officials in Washington agreed that the differences between the two sides mainly related to the details of the separation of India's civil and military nuclear facilities required under the deal, especially the status of its Fast Breeder Reactors.

They also indicated that the formula being worked out was for keeping the FBRs out of the purview of international safeguards for another six years till 2012. The Indian side is understood to have told the US that the FBRs would become operational only by 2010 and would need another two years thereafter to prove themselves.

The US response to this proposal would be known after Burns discusses it with Indian officials when he is in Delhi this week.

The FBRs are crucial to India's civil nuclear energy programme but US lawmakers also see them as an important element of the country's weapons programme and would like them to be brought under safeguards right away. The US government will be able to take the deal to Congress for ratification only if India comes up with a "credible and defensible" plan for separation of its civil and military nuclear facilities, the officials pointed out.

Before setting out for Delhi, just weeks after his last visit in January,  Burns told Newsweek that he was quite optimistic about sorting out the differences over the deal.

"We're 90 per cent of the way there," he told the magazine. He said though the negotiations had been "uniquely complicated, we are both committed to it, and as long as both of us show flexibility in the details, I'm confident that we will come to an agreement."