The resolution calls on the 191 UN member nations to stop terrorists, black market traders and all so-called "non-state actors" from acquiring such weapons or the materials and technology to make or deliver them.

It also calls on them to adopt laws to prevent sensitive materials and technology from getting into their hands.

The 15-0 vote approved the measure, crafted in months of negotations by the council's five permament members -- Britain, China, France, Russia and the United States -- all of which are nuclear powers.

The text was revised three times to answer objections from some of the council's 10 non-permanent members and finally won the support of the last holdout, Pakistan, which is also a nuclear-armed state.

US President George W. Bush first called for the resolution in September in a speech before the United Nations.

"Today's vote was an important step," White House spokesman Scott McClellan said. "This will help make the world safer and better."

Pakistani UN ambassador Munir Akram said his country strongly supported efforts to stop the spread of nuclear, biological and chemical weapons but underlined that the Security Council took on "exceptional responsibilities" in adopting the measure.

Diplomats said there was broad agreement on the need to close the loophole in existing international treaties on non-proliferation, which touch on states but not on individuals.

But many nations argued treaties were the better way to address the issue, and Pakistan in particular had raised concern about what actions might be taken to enforce the resolution's provisions.

After weeks of diplomatic haggling, the final draft said that the Security Council would monitor implementation and "take further decisions which may be required."

The mastermind of Pakistan's nuclear weapons programme, A.Q. Khan, confessed in February to passing nuclear secrets to Iran, Libya and North Korea. The United States said Tuesday it was seeking several other nations which may have been his "customers."

Akram again stressed Pakistan, which is not a party to non-proliferation treaties, would not allow inspections of its nuclear facilities, and cited without naming its nuclear-armed rival and neighbour India.

"Pakistan will not accept any demand for access, much less inspections, of our nuclear and strategic assets, materials and facilities. We will not share any information -- technical, military or political -- that would negatively affect our national security programmes or our national interests," he said.

US deputy ambassador James Cunningham said that all states must "maintain adequate controls over their nuclear material, equipment and expertise, not just states party to a specific treaty or supplier regime."

He said the council had responded "unanimously to a threat to international peace and security."

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