New Delhi, Sept 30 : UN nuclear watchdog chief Mohamed ElBaradei Wednesday warned against the "biggest threat" of nuclear weapons falling into the hands of extremist groups and asked India to lead global efforts towards nuclear disarmament.

"The biggest threat to the world remains ... extremist groups getting their hands on a nuclear weapon," ElBaradei told CNN-IBN, while alluding to Pakistani nuclear scientist A. Q. Khan's underground nuclear network that proliferated sensitive technologies to Iran and North Korea.

ElBaradei said the International Atomic Energy Agency (IAEA) has tried to "dry up" the A. Q. Khan network's illegal nuclear trade. But he was silent on Khan's links with the Pakistan government.

"To be honest we focused our energies on trying to ? dry up Khan's illegal nuclear trade network, and not so much on who he was working for," he said, while calling for more investigation into the activities of the Khan network.

ElBaradei asked India to lead efforts for complete nuclear disarmament but pointed out that the Nuclear Non-Proliferation Treaty (NPT) was not the perfect vehicle for this.

"I don't expect India to sign the NPT in its present form," he said. "Maybe the Comprehensive Test Ban Treaty (CTBT) would be more acceptable."

India has refused to sign both NPT and CTBT on grounds that they are discriminatory and tend to divide the world into nuclear haves and have-nots.

ElBaradei was conferred the Indira Gandhi Prize for Peace, Disarmament and Development by President Pratibha Patil Wednesday for his critical support in ending India's global nuclear isolation.

The UN nuclear watchdog chief said the world was looking to India for the future of nuclear energy research and development.

ElBaradei described the India-US nuclear agreement and the NSG nuclear waiver a "win-win deal for the world".

Speaking at an international atomic energy conference Tuesday, ElBaradei had hailed India as a "leading advocate" for nuclear disarmament, and asked the world to listen to its "voice" on eliminating nuclear weapons.

"India called for the elimination of all nuclear weapons as far back as 1948. It is important that India's voice should continue to be heard as a leading advocate for nuclear disarmament," he had said.

A day before representatives of the US, Britain, China, Russia, France and Germany meet in Geneva on the Iranian nuclear issue, ElBaradei said Iran was on the "wrong side of the law".

He was reacting to reports of a second uranium enrichment plant Iran had developed at Qom, which he described as a "setback" in the ongoing efforts to defuse the standoff over the Iranian nuclear programme.

"They have been on the wrong side of the law, you know in so far as informing the agency about the construction and as you have seen it, it has created concern in the international community," he said,

"I talked to Salehi, head of the energy organisation of Iran. He said the facility is far from being completed, there are no centrifuges in the facility, there is no nuclear material, it is simply still a ready construction.

"The world is ready to help Iran to make full use of nuclear energy for nuclear purposes. But Iran too needs to do its bit," he said.(IANS)