India on Monday embraced global nuclear disarmament and criticized major nuclear powers for urging restraint while sitting on big stockpiles of nuclear arms.

"A few nations are sitting on huge stockpiles of nuclear weapons," Indian Prime Minister Atal Behari Vajpayee told scientists at India's premier nuclear research centre, the Bhabha Atomic Research Centre."And insisting on collective restraint on the part of the rest of the world is an inherently unstable proposition," he told a ceremony marking 50 years of India's Atomic Energy Commission.

India defied international opinion in May to conduct two sets of underground nuclear tests, prompting neighbor and old foe Pakistan into carrying out its own nuclear tests in retaliation.

The tests raised fears that other nations might follow suit, endangering world security, but Vajpayee said India would use its new nuclear status to press for total disarmament.

"As an ancient nation of close to 1 billion people, India cannot be a party to the perpetuation of an unfair and iniquitous world order," Vajpayee said.

"Our status as a nuclear weapons power, we believe, enables us to pursue the goal of speedy nuclear disarmament with greater vigor and success."

Scientists on Monday presented Vajpayee with a rock from India's nuclear test site in the deserts of Rajasthan.

The international outrage at New Delhi's nuclear tests was led by the United States which imposed economic sanctions on India. Sanctions were also later slapped on Pakistan.

The major nuclear powers - the United States, Russia, China, Britain and France - jointly possess some 35,000 nuclear weapons.

They have made a vague commitment to abolish them one day, but believe that for now, residual stockpiles serve as a useful deterrent to each other and to countries that might seek to acquire atomic arms.

Vajpayee also hit out on Monday at a U.S. decision to deny visas to Indian scientists.

"It is unfortunate that attempts are made to put unwarranted restrictions on the participation of Indian scientists in international scientific conferences," he said.