With Pakistan's nuclear proliferation scandal exposed and peace moves with India under way, South Asia should be a safer place these days. But even as the United States vows to crush the atomic weapons black market and make civilian nuclear programmes safer, it is being seen as at least partly responsible for a growing arms imbalance between India and Pakistan that could have alarming consequences.

The risks raise the stakes as Indian and Pakistani officials met in Islamabad yesterday for the first formal peace talks between their countries in nearly three years, and the first since they came to the brink of war in 2002.

With U.S. blessing, analysts say, India is seeking to build its conventional and non-conventional weapons defences, making Pakistan feel increasingly vulnerable and driving it to make more and better weapons to counter its rival.

Pakistan is on the back foot after its top scientist, Abdul Qadeer Khan, admitted leaking technology and hardware to North Korea, Libya and Iran via a sprawling nuclear black market.

Analysts believe the scandal could make it harder for Pakistan to expand and upgrade its arsenal.

India is soon to sign a $1.1 billion deal with Israel for the delivery of three Phalcon early warning radar systems. India also wants the $2.5 billion Arrow anti-ballistic missile system from Israel, although no US clearance has been given.

"India's interest in Arrow is precisely to challenge Pakistan's nuclear deterrence," said Gary Samore of the International Institute for Strategic Studies in London.

"Pakistan is right to worry about the longer-term nuclear and conventional weapons threat from India, which is being allowed by Washington to acquire dual-purpose technology and increasingly sophisticated early warning systems."

For its part, Pakistan seeks to acquire second-hand F-16 fighters from Belgium after the United States refused to deliver 28 of the fighters in the 1990s due to concerns over Islamabad's nuclear programme.

Pakistani officials make no secret of their concern of the arms build-up by their neighbour.

"These are new elements being introduced in the India and Pakistan scenario," said military spokesman Major-General Shaukat Sultan. "They are going to result in an arms race and tilt the balance back in India's favour."

India already has a bigger army, a far more effective air force and more nuclear warheads.

According to Duncan Lennox, editor of Jane's Strategic Weapon Systems, India has around 50 nuclear warheads and Pakistan 25, although estimates vary widely on the secret arsenals.

The warheads can be fitted either to aircraft as bombs, or, more recently, to ballistic missiles. Lennox said India's defence acquisitions are made with China in mind, not just Pakistan.

Dr Pervez Hoodbhoy, a physicist and prominent anti-nuclear campaigner, doubts the effectiveness of anti-missile systems.

"The anti-ballistic missile system doesn't really work," he told Reuters. "India is making a mistake."

But he agreed that it did have a destabilising effect and could fuel the arms race nonetheless.

"Here the United States has much to be blamed for," he said.

As the imbalance widens, Pakistan will be encouraged to build more warheads and missiles to maintain what it calls its "minimum deterrence", analysts say.

Samina Ahmed, Pakistan director of the Brussels-based International Crisis Group, believes Pakistan's small nuclear arsenal is an effective deterrent to India, for now.

The further India gets ahead in an arms race, the more dangerous the situation becomes.

"The real problem lies not in Pakistan being unable to access technology, but when India decides to put its nuclear weapons in the field," Ahmed said. "That is when the arms race starts.

"It's very destabilising. If India fills in the gaps in its technology through this external assistance, it will encourage them to deploy. Do you think the Chinese will then sit back?"

In Pakistan, the proliferation scandal has pushed other issues to the background, at least for now.

While Pakistani President Pervez Musharraf has vowed to put his own house in order, questions remain over how secure the nuclear apparatus in the country is.

If Musharraf is to be believed, Pakistan's intelligence services knew little or nothing of Khan's misdemeanours.