A high-level panel called for sweeping reform of the United Nations (search) to tackle global threats in the 21st century and said the Security Council must authorize any pre-emptive or preventive military attack, which it refused to do in Iraq (search).

The panel's long-awaited report, which was commissioned by Secretary-General Kofi Annan (search) after last year's divisive diplomatic battle over the war against Iraq, said the dangers confronting the world today cannot be dealt with by any nation acting alone, even a superpower.

The 95-page report lays out a new vision for collective action to tackle threats to global security and puts "a more proactive" Security Council at the heart of a revitalized United Nations.

"The case for collective security today rests on three basic pillars," the panel said. "Today's threats recognize no national boundaries, are connected, and must be addressed at the global and regional as well as the national levels. No state, no matter how powerful, can by its own efforts alone make itself invulnerable to today's threats."

The issues facing the international community, the panel said, go far beyond fighting wars and must include campaigns to fight poverty, terrorism, environmental destruction, organized crime and weapons proliferation.

The U.N. Charter now permits the use of force for self-defense only in case of an attack or if authorized by the Security Council.

But the panel said the international community must now be concerned "about nightmare scenarios combining terrorists, weapons of mass destruction and irresponsible states ... which may conceivably justify the use of force, not just reactively but preventively and before a latent threat becomes imminent."

"The question is not whether such action can be taken: it can, by the Security Council as the international community's collective security voice, at any time it deems that there is a threat to international peace and security," the panel said.

It also broadened the global threats that could require military action to include the protection of civilians from genocide and other atrocities.

Whether the panel's wide-ranging recommendations attract substantial support remains to be seen. Its members include former top U.N. officials, the former prime ministers of Norway and Russia, the former foreign ministers of Australia and China, and former U.S. national security adviser Brent Scowcroft.

Annan plans to use the report as a basis for his own proposals in March to the U.N.'s 191 member states. He has invited world leaders to a summit in September to take action on U.N. reform and the new global agenda.

"We'll give it our careful consideration," U.S. Ambassador John Danforth said when asked about the report.

While the Security Council's refusal last year to authorize the U.S.-led war in Iraq served as the backdrop for the report, the panel only mentioned it as a case that sparked widely differing opinions and intense public attention. It said the U.S. decision to seek U.N. authorization — even in failing to win approval — had reaffirmed "the centrality" of the U.N. Charter.

The panel said any good argument for preventive military action should be put to the council in the future. If it refuses to authorize an attack, there will still be time to use persuasion, negotiation, deterrence and containment — and to try the military option again.

In what appeared to be a post-Iraq message to the United States, the panel said "for those impatient with such a response, the answer must be that, in a world full of perceived potential threats, the risk to the global order ... is simply too great for the legality of unilateral preventive action...."

The panel made 101 recommendations on how to achieve a more secure world. They range from expanding the U.N. Security Council from 15 to 24 members and defining terrorism to overhauling the international system to prevent the spread of nuclear weapons and authorizing a one-time buyout to put younger staff in top U.N. positions.

The panel declared the Nuclear Nonproliferation Treaty — the cornerstone of global security against atomic weapons — was "at risk" because of noncompliance and the spread of technology.

"We are approaching a point at which the erosion of the nonproliferation regime could become irreversible and result in a cascade of proliferation," the report warned.