With critics still claiming the deal will strike a possibly fatal blow to the Nuclear Nonproliferation Treaty (NPT), supporters described the agreement as crucial to a new stage in U.S. - India cooperation.

Revision of the Atomic Energy Act will allow the United States to sell India nuclear fuel and reactors for the first time in three decades, despite New Delhi's refusal to sign the NPT.

President Bush, who first proposed the deal in 2005, made approval by Congress a priority, saying India deserves to be recognized for its strong support of nonproliferation.

Indian leaders have contrasted their record with that of neighboring Pakistan, whose chief nuclear scientist A. Q. Khan was found to have spread nuclear information to countries such as Iran and North Korea.

New Jersey Congressman Rush Holt, a Democrat, delivered this impassioned statement in opposition to the U.S. - India deal.

"There will be a time when the history of the spread of nuclear weapons of mass destruction is written. And we will look back and see when the last thread of the nuclear nonproliferation regime was shredded with this agreement," he said.

Democrat Tom Lantos, who will head the House International Relations Committee, says the deal with India will not damage the NPT.

He said "This legislation is the exact opposite of nuclear proliferation. It opens up, for the first time in history, all of India's current civilian nuclear plans and all future nuclear plants, to international control. This is a control measure."

However, opponents insist that the agreement, which is also aimed at helping India devote resources to energy development, will free up nuclear fuel and resources for construction of additional weapons.

Democrat Ed Markey calls the deal weak, saying it will destroy nonproliferation efforts, and cites projections that India will increase production of nuclear bombs to 40 to 50 a year, which critics say will prompt similar efforts by Pakistan.

Markey also says other countries will be encouraged to seek what he considers the same weak standards in any agreements they negotiate.

"Wherever we set the standard, that is going to be the global standard," he said. " And when we turn to these other countries and tell them no, your standards are not high enough, they are going to call us hypocrites."

Republican Henry Hyde, whose name is attached to the House version of the legislation, disagrees.

"This is an excellent step forward. It recognizes the nuclear reality of India, and is a very progressive step," he said.

In working out the final version of legislation modifying U.S. law to allow technology transfers to India, lawmakers added language to ease concerns. The measure requires the president to determine that India provided what is called a credible plan to separate civilian and military nuclear facilities and programs.

Other requirements include progress by India and the International Atomic Energy Agency toward more thorough inspections, and cooperation with U.S. and global efforts to prevent the spread of enrichment and reprocessing materials.

The legislation also calls for India's full and active participation in U.S. efforts to dissuade, isolate and, if necessary, sanction Iran for its efforts to acquire weapons of mass destruction.