WASHINGTON (AP) - President Bush on Monday signed a civilian nuclear deal with India, allowing fuel and know-how to be shipped to the world's largest democracy even though it has not submitted to full international inspections.

"The bill will help keep America safe by paving the way for India to join the global effort to stop the spread of nuclear weapons," Bush said.

The bill carves out an exemption in U.S. law to allow civilian nuclear trade with India in exchange for Indian safeguards and inspections at its 14 civilian nuclear plants. Eight military plants, however, would remain off-limits.

"This is an important achievement for the whole world. After 30 years outside the system, India will now operate its civilian nuclear energy program under internationally accepted guidelines and the world is going to be safer as a result," Bush said in a bill-signing ceremony at the White House.

Critics have said the measure undermines efforts to curb the spread of nuclear weapons and technology and could spark a nuclear arms race in Asia by boosting India's atomic arsenal. India still refuses to sign the Nuclear Non-proliferation Treaty.

The measure passed Congress with bipartisan support, but critics complain the deal undermines efforts to prevent states like Iran and North Korea from acquiring nuclear weapons.

Rep. Ed Markey, D-Mass., a senior Democrat on the House Energy and Commerce Committee, said the pact, in effect, shreds the Nuclear Non-Proliferation Treaty. "This is a sad day in the history of efforts to halt the spread of nuclear weapons and materials around the world," he said. "The bill that President Bush has signed today may well become the death warrant to the international nuclear nonproliferation regime."

The White House said India was unique because it had protected its nuclear technology and not been a proliferator. The Bush administration said the pact deepens ties with a democratic Asia power, but was not designed as a counterweight to the rising power of China.

The administration also argued it was a good deal because it would provide international oversight for part of a program that has been secret since India entered the nuclear age in 1974. The deal also could be a boon for American companies that have been barred from selling reactors and material to India.

"India's economy has more than doubled its size since 1991 and it is one of the fastest-growing markets for American exports," Bush said.

In New Delhi, Prime Minister Manmohan Singh on Monday defended the nuclear deal, rejecting strong opposition criticism that it would lead to the dismantling of India's atomic weapons. He said he had some concerns about the legislation, but that they would be dealt with during technical negotiations on an overall U.S.-India cooperation agreement.

"The United States has assured us that the bill would enable it to meet its commitments" made in agreements struck in July 2005 and in March by Bush and Singh.

Singh said India would not accept new conditions and its nuclear weapons program would not be subject to interference of any kind because the agreement with the United States dealt with civil nuclear cooperation.

Earlier, opposition leader L.K. Advani of the Bharatiya Janata Party said India should not accept the U.S. legislation, saying that the deal would prevent India from conducting nuclear tests in the future. India conducted its first nuclear test in 1974 and followed it up with a series of nuclear tests in 1998.

"The primary objective is to cap, roll back and ultimately eliminate its (India's) nuclear weapons capability," Advani warned.

Before civil nuclear trade can begin, several hurdles remain. American and Indian officials need to work out a separate technical nuclear cooperation agreement, expected to be finished next year.

The two countries must now obtain an exception for India in the rules of the Nuclear Suppliers Group, an assembly of nations that export nuclear material. Indian officials must also negotiate a safeguard agreement with the IAEA.