Oct 2 (Reuters) - The U.S. Senate voted on Wednesday to approve a deal that would end a three-decade ban on U.S. civil nuclear trade with India. Here are some basic facts about the agreement. WHAT IS THE PACT?

* Overturning a 34-year-old ban, it allows the Asian power access to U.S. civil nuclear fuel and technology although it has never signed the Non-Proliferation Treaty, conducted nuclear tests in 1974 and 1998, and has not ruled out doing more.

* Under the amendment, India must separate its civil and military nuclear facilities, and submit civil facilities to inspections by the International Atomic Energy Agency.

* The agreement means other countries can sell India nuclear technology and fuel. France signed such a deal this week.

WHY IS IT CONTROVERSIAL?

* Critics say it undermines the NPT, membership of which has long been the guideline for the 45-nation Nuclear Suppliers Group (NSG) export cartel to provide civilian nuclear assistance.

* Critics also say it undercuts Washington's efforts to curtail Iran's nuclear programme and opens the way for a potential arms race in South Asia between India and Pakistan.

* India says 14 of its 22 nuclear facilities are civilian. The pact could make bomb-making easier at the other eight, as civilian nuclear fuel needs will be met by the United States.

WHO WILL BENEFIT?

* U.S. and European companies that supply nuclear technology and help build reactors. The deal could open up around $27 billion in investment in 18-20 nuclear plants over the next 15 years, according to Confederation of Indian Industry. * By 2030, the economic benefits that will accrue to India's economy as a result of nuclear trade could touch $500 billion, says Imagindia Institute, an Indian lobby group.

* India. It becomes a de facto nuclear power. New Delhi even says it still can test nuclear weapons if it needs to, although a waiver of NSG rules adopted to allow trade with India indicates this would be cut off if India tested again.

* India's economy. It relies on imported oil for some 70 percent of its energy needs and the government says nuclear power will help feed its rapidly expanding economy.

* Washington. The deal will mean deeper ties between Washington and Delhi just as India starts to embrace the West. It is not just about friendship -- the United States, for example, may now have a better chance of winning a $10 billion fighter deal from India, the world's biggest arms contract.

WHO WON'T BENEFIT?

* Pakistan, India's nuclear rival, has sought a similar deal with Washington but was refused because of a poor non-proliferation record. As a result, Islamabad has talked of expanding nuclear cooperation with China. Pakistan has not signed the NPT.

* China. Some analysts see the India deal as part of attempts by the United States to counterbalance China's influence in Asia. * The environment. The deal will still have a minimal impact on India's power industry. Dirty coal-fired power stations and hydroelectric dams will continue to account for the lion's share of its power generation.

IS THE DEAL POPULAR IN INDIA?

* Polls show most Indians are far more worried about the economy and inflation than some abstract nuclear deal.

* The powerful communists withdrew their support for the Congress-led government over the deal, saying it made India a pawn of Washington. Hindu nationalists also oppose the deal, saying it limits India's ability to test nuclear weapons.

* Nevertheless, the deal is seen as one of Prime Minister Manmohan Singh's biggest achievements in four years in power. (Compiled by Alistair Scrutton; Editing by Jeremy Laurence and Jerry Norton)

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