Manmohan faces tough grilling over US trip

While some experts say President George Bush's decision to allow civilian nuclear sales to India will help solve the vast energy needs of one of Asia's fastest-growing economies, there has been mounting domestic criticism the agreement could hurt national security.

The opposition Hindu nationalists say the accord reached during Singh's visit puts a ceiling on India's nuclear arsenal and New Delhi would lose "flexibility" in deciding its weapons strategy. They vowed over the weekend to make it a central issue during the new parliamentary session.

Former premier Atal Behari Vajpayee said Bush "merely made promises" -- Congress can still scupper the deal pledging US aid for energy-hungry India's fledgling civilian atomic power programme -- but Singh made "long-term and specific commitments" that have security implications for the nation.

India was denied access to large nuclear reactors and fuel as a result of sanctions imposed after it conducted nuclear tests in 1974 and later in 1998.

Singh agreed to separate India's civilian and military nuclear programmes, open its facilities to outside scrutiny and work to prevent nuclear proliferation.

"Though we believe in minimum credible deterrent, the size of the deterrent must be determined from time to time on the basis of our own threat perception. This is a judgement, which cannot be surrendered to anyone," said Vajpayee, who led India through nuclear weapons tests in 1998.

While New Delhi's relations have warmed considerably with rival Pakistan, it is still deeply wary of its nuclear-armed neighbour with which it has fought three wars. India has also fought a brief border war with China in 1962.

India's communist allies on whom Singh's Congress party relies for survival in parliament have also attacked the agreement, saying it could hamper "the pursuit of an independent nuclear technology policy."

Supporters of the deal say it will end India's pariah status since it first tested nuclear weapons and refused to sign the Nuclear Nonproliferation Treaty, and shifts it closer to international acceptance as a nuclear-armed nation.

But critics say India has lived long enough without such acceptance and does not need it now.