Negotiations will commence 'very shortly' with the US on a bilateral agreement to operationalise the civil nuclear deal during which India will flag its concerns with regard to the law passed by the American Congress on the issue, Prime Minister Manmohan Singh said on Monday.

Returning from the India-ASEAN and East Asia Summits in the Philippines, he told accompanying journalists that 'there are issues. There are concerns. We have to discuss (these) with the US administration'.

"Some of these things will be addressed in the 123 (Bilateral) Agreement on which negotiations will be held very shortly," Dr Singh said.

New Delhi has said it had 'genuine reasons' for concern over certain elements in the recently-enacted US law like conditional access to reprocessing technology and silence on the issue of reprocessing of spent fuel.

The government has made it clear that India will not accept any legally binding provision on future nuclear testing in the 123 Agreement and that it will 'walk out' of the deal if it seems to undermine its national interest at any point.

Dr Singh said there was general support that civil nuclear energy be considered as an option to meet the need for clean energy and that this deserved greater attention of the international community.

The prime minister's special envoy on nuclear issue Shyam Saran had said last week that there are 'very very important issues which need to be addressed' and that the talks on 123 Agreement were going to be difficult.

"We have to continue discussions on the 123 Agreement. There are certain important issues we need to look at," said Saran, the former foreign secretary who has been India's negotiator on the deal.

He, however, said, "We have dealt with difficult issues in the past and so I am optimistic. The mindset on both sides is one of problem-solving and if this continues, there is room for optimism."

He said India continued to lobby for support among the Nuclear Suppliers Group countries and was now 'better placed' in the 45-nation grouping, with several countries earlier having negative positions softening their stance. But that does not mean that problems are over and 'we need to work with all members', he said.