Addressing world leaders for the last time as secretary-general, Kofi Annan painted a grim picture Tuesday of an unjust world economy, global disorder and widespread contempt for human rights, and appealed for nations and peoples to truly unite.

As the annualGeneral Assembly ministerial meeting got under way, the 192 U.N. member states faced an ambitious agenda including trying to promote Mideast peace, curb Iran's nuclear ambitions, get U.N. peacekeepers into the conflict-wracked Darfur region of Sudan, and promote democracy.

In a new blow to global stability, Thailand's military launched a coup against Prime Minister Thaksin Shinawatra even as Annan spoke. The Thai prime minister, who was in New York, switched speaking slots with Montenegro so he could address the General Assembly on Tuesday evening, a day earlier than planned.

U.S. President George W. Bush took the podium for a speech aimed at building bridges with people in the Middle East angry with the United States over Iraq and Lebanon. He laid out a vision for peace and assured Muslims that the United States is not waging war with Islam.

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On the sidelines, Bush pressed Iran to return at once to international talks on its nuclear program and threatened consequences if they do not.

Bush's speech was less confrontational on that subject. He said Iran "must abandon its nuclear weapons ambitions," and return at once to international talks on its program. The U.S. has threatened sanctions if Iran does not suspend uranium enrichment.

Iranian President Mahmoud Ahmadinejad — who was scheduled to speak to the body later Tuesday — was not in the hall during Bush's address.

Annan, whose second five-year term ends on Dec. 31, said the past decade had seen progress in development, security and the rule of law — the three great challenges he said humanity faced in his first address to the General Assembly in 1997.

But the secretary-general said too many people are still exposed to brutal conflict, and the fear of terrorism has increased the risk of a clash of civilizations and religions. Terrorism is being used as a pretext to limit or abolish human rights, and globalization risks driving richer and poorer peoples apart, he said.

"The events of the last 10 years have not resolved, but sharpened, the three great challenges I spoke of — an unjust world economy, world disorder, and widespread contempt for human rights and the rule of law," Annan said. "As a result, we face a world whose divisions threaten the very notion of an international community, upon which this institution stands."

"I remain convinced that the only answer to this divided world must be a truly United Nations," he said.

In his annual report, Annan touched on some of the most difficult issues confronting the leaders from countries large and small assembled in front of him.

He said the Arab-Israeli conflict is the most potent and emotionally charged conflict in the world today.

"As long as the Palestinians live under occupation, exposed to daily frustration and humiliation, and as long as Israelis are blown up in buses or in dance halls, so long will passions everywhere be inflamed," Annan said.

The secretary-general warned that as long as the U.N. Security Council is unable to end the conflict and Israel's 40-year occupation by bringing both sides to accept and implement its resolutions "so long will respect for the United Nations continue to decline."

"So long, too, will our impartiality be questioned," he said. "So long will our best efforts to resolve other conflicts be resisted, including those in Iraq and Afghanistan, whose peoples need our help just as badly, and are entitled to it," he said.

Annan also decried the continuing conflict in Sudan's western Darfur region, "where the continued spectacle of men, women and children driven from their homes by murder, rape and the burning of their villages makes a mockery of our claim, as an international community, to shield people from the worst abuses."

As he neared the end of his speech, Annan's voice rose with emotion, describing his "difficult and challenging but at times also thrillingly rewarding" job.

"Together we have pushed some big rocks to the top of the mountain, even if others have slipped from our grasp and rolled back. But this mountain with its bracing winds and global views is the best place on earth to be," Annan said.

He said he would "miss the mountain" and "when all is said and done, the world's most exalting job."

"I yield my place to others with an obstinate feeling — a real obstinate feeling — of hope for our common future," Annan said, again visibly moved.

The presidents, prime ministers, foreign ministers, ambassadors and other diplomats in the chamber then burst into loud applause and rose to give Annan a sustained standing ovation.

Even before the start of the so-called General Debate, ministers were meeting on some of the key issues.

A Security Council meeting on Monday focused on overcoming Sudan's resistance to allowing the United Nations to take control over peacekeepers in Darfur. Israeli Foreign Minister Tzipi Livni met Palestinian President Mahmoud Abbas late Monday, and the Security Council was to hold a meeting Thursday that Arab leaders hope will help revive the Mideast peace process.

Shortly before coming to New York, France's President Jacques Chirac proposed a compromise to kick-start talks between Iran and the international community, suggesting the threat of U.N. sanctions be suspended in exchange for Tehran halting its uranium enrichment program.

The African Union's Peace and Security Council is scheduled to meet Wednesday in New York to discuss breaking the deadlock over Darfur, with the Sudanese government refusing to allow U.N. peacekeepers to take over the security situation from the AU.

But the undercurrent of this year's debate will be the race to succeed Annan. The six candidates were already making appearances Monday, and many more were planned.

Brazil's President Luiz Inacio Lula da Silva focused on another key issue — meeting the goal set by the U.N. Millennium Summit in 2000 of reducing extreme poverty by half by 2015.

"All here know that some 840 million human beings — nearly one out of seven in the planet — do not have enough to eat," he said. "Fifty billion additional dollars each year are needed to reach the Millennium Development Goals on time. The international community can afford it."

South African President Thabo Mbeki echoed Lula, saying "billions of poor people are increasingly becoming impatient because every year they hear us adopt declaration after declaration, and yet nothing practical is done to assuage the hunger pains that keep them awake at night."