Seeking to conclude the bilateral nuclear agreement at the earliest, India and the US on Wednesday narrowed down differences on various issues as they wrapped up the first round of official-level talks in New Delhi with "good progress".

• Indo-US nuke tango

After three days of tough negotiations on issues like atomic fuel supply, storage, export control and sale of technology, the two sides decided to hold "fairly soon" the second round of discussions to conclude the Peaceful Nuclear Cooperation Agreement, also called 123 Agreement.

The two sides had "very productive discussions", sources told PTI.

• Support the N-deal

The two countries made "good progress towards reaching an agreed text" on the pact, the sources said.

The first round of formal talks saw the two countries discuss contentious issues like future nuclear testing by India and assurances on atomic fuel supplies by the US.

At the talks, the Indian side was led by S Jai Shankar, joint secretary (America) in the external affairs ministry, while the US delegation was headed by Richard Stratford, director of the Department of Energy.

The Indian delegation also comprised officials from the Department of Atomic Energy, while the US side includes representatives from the State Department and Bureau of Security and Non-proliferation.

The US side appeared satisfied with the talks, the sources said.

The officials of the two countries will now report to their respective governments and finalise the date for the next round of talks.

During the first round of formal talks, the two countries narrowed down differences on various aspects, including the quantity of fuel that can be stored by India after import of fuel starts, the sources said.

"The first round has been positive and constructive," they said adding, both sides expressed desire to conclude the agreement at the earliest.

Further discussions will have to be held on contentious issues like nuclear testing by India in future and assurances by the US on uninterrupted fuel supplies.

In the proposed agreement, the US has been seeking inclusion of a clause which says that cooperation will be snapped if India were to conduct a nuclear test in the future.

Washington's insistence in this regard comes in the backdrop of intense pressure from US lawmakers and experts.

New Delhi has refused to accept it, saying it has already declared unilateral moratorium on nuclear tests and its commitment in this regard has been mentioned in the July 18 Joint Statement with the US.

India does not want to give a legal status to its unilateral moratorium by including it in the agreement. It points out that the US law already has a clause, which states that Washington will snap ties with a country that explodes a nuclear device.

On its part, New Delhi is willing to reiterate in the bilateral agreement its assertion on unilateral moratorium on nuclear testing and a middle path is being found.

The two sides also have to reach an understanding on India's insistence on the US giving assurances on uninterrupted nuclear fuel supplies.