External Affairs Minister Pranab Mukherjee and US Secretary of State Condoleezza Rice put the final seal on the agreement at an impressive ceremony held in the Benjamin Franklin Room of the State Department, culminating a crisis-ridden process initiated on July 18, 2005 in Washington during Prime Minister Manmohan Singh's visit for talks with US President George W. Bush.

"Both India and the US Administration have now completed all our internal procedures to be able to sign this path breaking agreement," Mukherjee said after signing the agreement, paving the way for entry of American companies into the Indian nuclear market after three decades.

"Today is an important day for India-US relations, for global energy security and for our common endeavour to promote sustainable development while addressing environmental challenges," he said at the ceremony held at the State Department.

Noting that the agreement reflects a "careful balance of rights and obligations", he said "its (agreement's) provisions are now legally-binding on both sides once the agreement enters into force."

This comment assumes significance since the US had said that the contents of the 123 Agreement were a political commitment and not legally binding, triggering concerns in India over aspects like promises on nuclear fuel assurances.

He said the importance of the Agreement is that it was the first step to civil nuclear cooperation and trade between India and the US.

"It is also the first step to India's cooperation with the rest of the world in civil nuclear energy," he said.

He said the signing of the agreement has brought to fruition three years of "extraordinary effort" by both India and the US and it was "one more visible sign of the transformed relationship and partnership" that the two countries are building.

"We now look forward to working with US companies on the commercial steps that will follow to implement this landmark agreement," Mukherjee said.

The External Affairs Minister described the agreement as the first step to India's cooperation with the rest of the world in civil nuclear field.

By reinforcing and increasing the nuclear element in the country's energy mix, which is vital to sustain India's growth rate, nuclear power will directly boost industrial growth, rural development and help expand every vital sector of the country's economy, he said.

"It enables India to respond with her global partners to the challenges of climate change and global warming by strengthening her own economic growth and sustainable development," he said.

Mukherjee said the wide-ranging initiatives announced by Prime Minister Manmohan Singh and President George W Bush in July 2005 and March 2006 have led to a transformed relationship between the two countries.

Praising Bush, Rice and the American Congress besides the Indian-American community for making the agreement a reality, the External Affairs Minister said New Delhi looks forward to working with Washington in other fields as well.

He listed these as combating terrorism, containing and fighting pandemics, climate change, ensuring food security, cooperating in disaster relief operations and other regional and global initiatives.

Earlier, Rice said that the 123 Agreement was unprecedented and demonstrates the vast potential for strategic partnership between India and the United States. She said the nuclear deal is not just nuclear cooperation.

"Today we look to the future, a shared future. Let us use the partnership to fight against terrorism, to try a new socialist agenda for the 21st century."

"India and the US can do all these together. Now there is nothing we cannot do," the Secretary of State said. Prime Minister Singh "literally risked his political future" for the Indo-US nuclear agreement and remade his government again with the support he needed, Rice said, referring to the withdrawal of support to the NDA government by the Left parties.

The formal signing ceremony of the bilateral agreement could not take place during Rice' visit to New Delhi last week due to India's concerns on certain riders in the US Congressional legislation on the nuclear deal, is being held after US President George W. Bush assured New Delhi that the new law makes no changes on fuel supply assurance commitments or the terms of the 123 agreement.

India's Cabinet Committee on Political Affairs also gave the go ahead to Mukherjee to sign the agreement after approving the pact initiated by Prime Minister Manmohan Singh and Bush in 2005.

The signing ceremony was attended among others by India's Ambassador to the US, Ronen Sen and senior State Department officials.

Describing the 123 Agreement as "unprecedented", Rice said it demonstrated the vast potential partnership between India and the United States.

"The world's largest democracy and the world's oldest democracy joined together by our shared values and increasingly by many shared interests now stand as equals closer together than ever before," she said.

Rice said that US President Bush first saw the potential for the need for transforming the US-India partnership in 1999 when he was still the Governor of Texas and he made it one of his highest priorities.

"That's what democratic leaders do. They deal with the world as it is but they lay out a vision of a world as it could be. A vision of a new better reality and they lead their nations to expand the scope of the possible," she said.

"I know I speak for my friend foreign minister Mukherjee when I say how honoured we are to serve such leaders and to play the roles we have in hoping to shape this diplomatic triumph for both our nations. Let no one assume though that our work is now finished. Indeed, what is most valuable of this agreement is how it unlocks a new and far broader world of the potential for strategic partnership in this 21st century," the top US diplomat said.

"Let us share this partnership to shape an international order in which all states can exercise their sovereignty securely, responsibly and in peace," Rice said.

"Let us use this partnership to tackle the great global challenges of our time-- energy security and climate change, terrorism and violent extremism, she said.

"Let us use this partnership to protect and promote our common values, human rights and human dignities, democracy, liberty and the rule of law for people who are diverse in background but joined together in spirit and aspirations."

"India and United States can do all of these, and more together. There is so much that the two great nations will achieve in this new century," Rice added.