India and the United States on Tuesday concluded their two-day talks on an agreement to operationalise the civilian nuclear deal.

There were indications that the two sides had narrowed down differences.

Further rounds of discussions will be held in due course of time to firm up the bilateral agreement, called 123 Agreement, with both sides hoping to conclude by the end of this year, sources said.

At the technical-level talks, officials of the two countries sought to iron out differences over various elements, including fuel supply assurances, reprocessing of spent fuel and future nuclear testing by India.

The two sides understood each other's position and there was some narrowing down of differences, sources said.

New Delhi has alleged that the Henry Hyde Act, passed by the US Congress in December last year to allow civil nuclear trade with India, "significantly deviates" from the understandings of July 18, 2005, and March 2006, which was unacceptable to it.

India has made it clear that it will accept no deviation from the understanding reached between the two sides last year.

New Delhi has already conveyed its concerns to Washington and handed over a draft text of the agreement suggesting the clauses it wants to be incorporated.

At the talks, the Indian side was led by S Jai Shankar, India's high commissioner to Singapore who had been involved in the talks earlier as Joint Secretary (Americas).

His successor Gayatri Kumar and officials of the Department of Atomic Energy (DAE) also attended the parleys.

Richard Stratford, director of Nuclear Division in the State Department, headed the US side.