President Bush today won the backing of the UN's nuclear watchdog for a controversial deal to end India's status as a nuclear pariah and give it access to Western technology and fuel supplies to develop its civil nuclear power programme.

The deal was finalised in negotations overnight and announced by Mr Bush in New Delhi after talks with Manmohan Singh, the Indian Prime Minister.

Under the agreement, designed to help India meet its surging energy needs, New Delhi will separate its civil nuclear programme from its military programme and open all designated civil facilities to international inspection.

Crucially, though, India will not have to sign up to the Nuclear Non-Proliferation Treaty (NPT), the 1968 pact that restricts the spread of nuclear weapons.

China, one of five states allowed nuclear weapons under the NPT, criticised the deal, as did Pakistan, India's nuclear rival in South Asia, which demanded equal treatment. Mr Bush is due to travel to Pakistan at the weekend in the next stage of his visit to South Asia, despite a suicide bomb attack this morning which killed five people, including a US diplomat, in Karachi.

Mr Bush is also expected to meet opposition from the US Congress, which must ratifiy the treaty since it involves a change in US law to allow the export of nuclear technology to India. The deal must also be approved by the Nuclear Suppliers' Group, an informal group of 45 nations that controls the trade in nuclear technology and fuel.

Critics of the deal, in America and elsewhere, have complained that it is at best a side-deal to the NPT and at worst will encourage other states to develop nuclear weapons programmes in defiance of the non-proliferation regime.

But the deal quickly won the valuable support of Mohammed ElBaradei, director-general of the International Atomic Energy Agency, who said that it would help satisfy India's growing energy needs and would be a "step forward towards universalisation of the international safeguards regime".

While opponents of the deal argue that it undermines non-proliferation goals, Mr ElBararadei said it would help "consolidate the non-proliferation regime, combat nuclear terrorism and strengthen nuclear safety".

Under the deal, India will place 14 of 22 nuclear power reactors under international safeguards, an Indian official said. India currently has 15 reactors producing 3,310 megawatts of electricity and seven others under construction that would increase output to 6,730 megawatts.

Six of the fourteen slated for civilian status, including two under construction, are already under International Atomic Energy Agency (IAEA) safeguards. The rest will be deemed civilian under a phased programme to be completed by 2014.

The deal leaves eight nuclear reactors for military uses and Washington agreed today to let India develop an experimental plutonium-based fast breeder power reactor program without international inspection. Plutonium can be also used to make nuclear weapons.

"We concluded an historic agreement today on nuclear power," Mr Bush said in the news conference with Mr Singh. "It’s not an easy job for the Prime Minister to achieve this agreement. I understand. It’s not easy for the American President to achieve this agreement."

The deal represents a major shift in policy for the United States, virtually according India nuclear power status. Washington imposed temporary sanctions on India in 1998 after it conducted nuclear tests but has since enjoyed a diplomatic and economic rapprochement.

Mr Singh repeatedly thanked the US President for personally shepherding through the deal. "But for his leadership, this day probably would not have come so soon," he said.

The deal caused consternation in Pakistan, where US officials made it clear that the Pakistani Government should not expect the same kind of treatment.

Nicholas Burns, the Under-Secretary of State who headed the US negotiating team in India, said that the deal was "unique".

"What distinguishes India is that India has protected its nuclear technology over the 30 years of the Indian nuclear programme - India has not proliferated. Unlike North Korea which has been a major proliferator," Mr Burns said.

"India has brought itself into conformance with all the international guidelines pertaining to nuclear technology, unlike Iran for instance which has been a great violator of those international programmes," he said.

Ahead of Mr Bush's visit to Pakistan, a US diplomat was one of five people killed in a suicide bomb attack. The bomber appeared to have driven a car packed with explosives directly into the diplomat's own vehicle, ripping through the parking lot of the Marriott Hotel and shattering windows both the hotel and the nearby US Consulate. Fifty-two people were injured in the attack.

Mr Bush said he would not be deterred. "We have lost at least one US citizen in the bombing, a foreign service officer, and I send our country’s deepest condolences to that person’s loved ones and family," he said. "Terrorists and killers are not going to prevent me from going to Pakistan."

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