With the world facing challenges posed by poverty, recession, global warming and nuclear proliferation, among others, “we have already waited too long,” Mr. Sarkozy said at the 192-member Assembly’s annual high-level debate.

“The most developed countries cannot govern mankind on their own,” he said. “Whole countries cannot be left out, nor billions of people who now aspire to play their part on the world stage.”

The leader of France, one of the five permanent members with veto power at the Security Council, called for expansion of its membership.

“It is unacceptable that Africa does not have a permanent member of the Security Council, or to exclude South America, with such a great power as Brazil, or India with its population of 1 billion, or Japan or Germany.”

An agreement on at least provision reform must be reached by the end of this year, Mr. Sarkozy said, with “the legitimacy of the UN riding on this reform.”

Also in urgent need of restructuring are the International Monetary Fund (IMF) and the World Bank in the face of the current economic turmoil, with voting rights being equally distributed among nations, he emphasized. Additionally, the international monetary system must be transformed to include more than just one currency as the world becomes increasingly more multipolar, both politically and economically.

On climate change, the French President said that a new agreement on curbing greenhouse gases is essential in December in Copenhagen, Denmark.

“This cannot be put off any longer,” he said, calling for the creation of a new World Environment Organization to replace the current disparate committees and groups, numbering in the dozens.

“The threats of the worst crises are not behind us, but ahead of us,” Mr. Sarkozy stated. “We are at one of those moments in history where political decisions have a profound and lasting impact on the future. We have no choice; we must take risks and act, since the greatest risk today would be to do nothing, to let ourselves be carried along by the force of habit, to take our time.”

Also calling for Security Council reform today was Italian Prime Minister Silvio Berlusconi, who said it is necessary to make the body “more effective and representative.”

However, he cautioned in his address to the Assembly, adding new permanent members to the Council “would simply increase the sense of exclusion of all the countries that contribute actively to international peace and security and of the new countries that in the future could assume growing responsibilities.”

Also requiring reform is economic governance, Mr. Berlusconi said, which must take into account the voices of more countries.

“This action must, of course, respect the central role of the United Nations, starting with its most representative organ: the General Assembly.”

News Tracker: past stories on this issue

UN panel calls for new global reserve, credit systems to avert future crises