India has hailed a nuclear co-operation deal with the United States, seen as a major shift in Washington's policy.
Manmohan Singh will deliver an address to Congress on Tuesday
President George W Bush says he will ask Congress to lift sanctions on India that will give Delhi access to civilian nuclear technology.
The deal came during a visit by Indian Prime Minister Manmohan Singh, who is to deliver a speech to a joint meeting of Congress on Tuesday.
The US tightened nuclear curbs on India after Delhi's weapons tests in 1998.
The BBC's Brajesh Upadhyay in Washington says Indian officials are calling the agreement a major triumph for Mr Singh, who is on his first official visit to the US.
A joint statement issued after Monday's meeting between President Bush and Mr Singh said that the US would work to achieve full civil nuclear energy co-operation with India.
Mr Singh's spokesman, Sanjay Baru, told the BBC: "It's a historic declaration and all the nuclear sanctions imposed on India have been lifted."
Delhi had been anxious to strike a deal on ways to share nuclear technology to help meet its growing energy needs.
The deal was agreed despite India's continued refusal to sign an international nuclear non-proliferation treaty (NPT), designed to halt the spread of nuclear weapons.
The joint statement said: "As a responsible state with advanced nuclear technology, India should acquire the same benefits and advantages as other states."
However, US undersecretary of state for political affairs Nicholas Burns insisted the deal "does not mean that US is now recognising India as a nuclear weapons state".
"That's a separate matter. India is not part of the NPT."
A senior US official said India had asked for such recognition but the US refused because of the treaty issue.
Observers say the deal is an important shift in US foreign policy and shows Washington is comfortable that Delhi is committed to preventing proliferation, despite not signing the treaty.
The nuclear deal has already sparked some opposition in the US
The deal has already sparked some opposition in Congress.
Democrat representative, Ed Markey, said: "We cannot play favourites, breaking the rules of the non-proliferation treaty, to favour one nation at the risk of undermining critical international treaties on nuclear weapons."
Joseph Cirincione of the Carnegie Endowment for International Peace, said: "This is the triumph of great power politics over non-proliferation policy."
Later on Tuesday, Mr Singh is to be afforded the rare honour of addressing a joint meeting of Congress - only the eighth foreign leader to do so in five years.
At a White House dinner on Monday, President Bush told Mr Singh: "The relationship between our two nations has never been stronger."
Secretary of State Condoleezza Rice said: "Today the president had an opportunity to tell the prime minister that we value greatly India as an international partner."
The trip has not been a total success for Mr Singh, however.
He has failed to get President Bush's support for a permanent seat for India on the United Nations Security Council.