The United States on Wednesday reported 90 per cent progress towards finalisation of an agreement to operationalise the civilian nuclear deal with India but said both countries needed to make 'compromises' to sort out remaining differences.

Under Secretary of State Nicholas Burns, key negotiator of the deal from the US side, said he would be travelling to India in the next week or two for talks and that a 'major effort' was expected in near future to firm up the agreement.    

"We have made enormous progress (on talks on the 123 agreement)... We are 90 per cent there," he said, addressing a function at the Heritage Foundation in Washington.

Noting that it had taken 'longer than we thought' to finalise the agreement, talks for which started two years ago, Burns said he was looking forward to his upcoming visit to India for the 'final effort.'

He said the civil nuclear agreement, that will symbolically represent growth of Indo-US relations, was a 'enormously complex' issue and had been going through intense scrutiny in Indian Parliament as was expected in a democracy.

He, however, expressed confidence that the two sides will be able to conclude the agreement.

Finalisation of the 123 agreement has got delayed due to differences on issues like reprocessing right, perpetuity of fuel supplies and continuance of the civilian nuclear cooperation if India were to conduct an atomic test.

"It is going to require a little hard work... There will be need for some compromises by both the sides to complete the deal," the US under secretary said, adding that both sides were keen to conclude the agreement. "I am confident we will do it."

Burns said the technical-level discussions between the two countries in London, which concluded on Tuesday, had also witnessed a 'lot of progress.'
 
He said he will hold talks with the US delegation and then call up Foreign Secretary Shivshankar Menon in a day or two before deciding on date of his visit to India. The US official said India had sought certain clarifications on the Hyde Act passed by the Congress in December and these were being addressed in the ongoing negotiations.

Burns said the nuclear agreement is 'too important for both governments to let go.'