US and Indian technical experts made little progress when they met in London this week in another attempt to work through persistent serious differences over a nuclear cooperation agreement, a US official said on Tuesday.
The official, who declined to be identified, told Reuters he had not received a full report on the talks but "there was not a lot of progress" when negotiators met on Monday.
The much-heralded agreement would give India access to US nuclear fuel and reactors for the first time in 30 years, even though New Delhi tested nuclear weapons and never signed the Nuclear Non-Proliferation Treaty.
On May 1, the two countries claimed extensive progress during two days of talks in Washington aimed at salvaging their landmark deal, and Undersecretary of State Nicholas Burns, the chief US negotiator, said he would "visit India in the second half of May to reach closure."
But last week Burns postponed his trip, and the decision was made to send technical experts to London to continue working on the issues.
The deal is the touchstone of new US -India relationship that Washington envisions as a pillar of 21st century international security, but its history has been rocky.
Obstacles have included a US Congress mandate that Washington halt nuclear cooperation if India tests a nuclear weapon as it did in 1998.
Other disputed points have been US refusal to give India prior approval to allow reprocessing of spent fuel with US components and to assure permanent fuel supplies.