Prime Minister Manmohan Singh told parliament the landmark deal struck with President George W. Bush when he visited Washington in July giving New Delhi access to civilian atomic technology was a "binding commitment."

The agreement would extend full US civilian nuclear energy cooperation to New Delhi, denied access to nuclear technology since 1974 when it first tested a nuclear weapon and refused to sign the Nuclear Nonproliferation Treaty.

US Congressional critics complain the agreement undermines international nuclear non-proliferation efforts and needs to be stricter.

The Indian prime minister was seeking to allay speculation that Washington had been asking for more concessions and that New Delhi might give in to gain US civilian nuclear cooperation.

Energy-import dependent India is seeking to increase its fuel sources to sustain its booming economy. Nuclear power supplies around three percent of the fuel needs of the nation of more than one billion people, but it hopes to increase that figure to around 20 percent within two decades.

For the United States, the deal has been a key step in improving ties with India which it sees increasingly as a counterweight to China.

Singh said the agreement with the US would proceed on the basis of "strict reciprocity."

"If the US does not carry out its obligations, we are also free not to carry out our obligations," Singh told the upper house.

He said he was referring to provisions under the pact in which the US said it would seek Congressional agreement to change US laws and work with other nuclear nations to enable full civil nuclear energy cooperation with India.

For its part, Singh has said India would "reciprocally agree" and be ready to assume the same responsibilities as other leading countries with advanced nuclear technology.

These included the separation of civilian and military nuclear facilities and programmes in a phased manner and filing a declaration about its civilian facilities with the International Atomic Energy Agency.

Junior foreign minister Rao Inderjit Singh said the pact's implementation would be guided "fully and entirely" by commitments in the July joint statement by Bush and the Indian prime minister.

"It has been made very clear to the US... that our commitments and obligations would only be those that have been spelt out in the joint statement," he said, adding the two sides were working to lay down a roadmap.

"Our commitments would be conditional upon, and reciprocal to the US fulfilling its side of this understanding," the minister said.

Prime Minister Singh said a second meeting of the Nuclear Working Group would be held later this month. The meeting is slated to be held in Washington.

The group headed by Foreign Secretary Shyam Saran and US Undersecretary of State for Political Affairs Nicholas Burns met for the first time October 21 in New Delhi and Singh described it as a "good meeting".

The US State Department has said it was confident Congress would approve the deal.

Western opponents of the deal say it does not justify making big exceptions to US law and international non-proliferation practices. However, proponents say a move to insist on the deal's renegotiation could result in its collapse.

Proliferation experts say the deal could undermine US efforts to get North Korea and Iran to curtail their nuclear programmes.

North Korea has already declared itself a nuclear power while Iran has said it is only seeking to develop a civilian nuclear programme and is not trying to build nuclear weapons.