Secretary-General Ban Ki-moon warned kings, prime ministers and presidents Thursday of growing political polarization and social inequalities and implored U.N. members to show greater tolerance and mutual respect to bring the world together.
In his keynote speech to the opening of the General Assembly's annual ministerial meeting, the U.N. chief told leaders from the 192-member nations that "today, we are being tested."
Ban said people everywhere are living in fear of losing their jobs, too many are caught in conflict, "and we see a new politics at work — a politics of polarization."
"We hear the language of hate, false divisions between 'them' and 'us,' those who insist on 'their way' or 'no way,'" he said.
In times of such polarization and uncertainty, Ban said, "let us remember, the world still looks to the United Nations for moral and political leadership."
The meeting follows a three-day summit to promote the achievement of U.N. anti-poverty goals by 2015 that wrapped up late Wednesday night. Many leaders who attended that summit remained in New York for the ministerial session, and will shift gears to other world issues from the continuing impact of the global financial crisis to terrorism and nuclear proliferation.
Thursday's session heard from President Barack Obama in the morning. Iranian President Mahmoud Ahmadinejad speaks in the afternoon as key nations try to bring Iran to the negotiating table over it's nuclear program.
In his speech, Obama said "the United States and the international community seek a resolution to our differences with Iran, and the door remains open to diplomacy should Iran choose to walk through it."
"But the Iranian government must demonstrate a clear and credible commitment, and confirm to the world the peaceful intent of its nuclear program," the U.S. leader said.
Ban urged Iran "to engage constructively with the international community and comply fully with Security Council resolutions" calling for Tehran to suspend uranium enrichment and return to talks.
The secretary-general also touched on many other global issues — urging North Korea to return to six-party talks on its nuclear program, calling on Israel and the Palestinians not to take any action that would hold back progress on peace talks, urging progress on nuclear disarmament where "we see new momentum," and declaring again the climate change remains the world's "defining challenge."
Just ahead of Obama's speech, Brazilian Foreign Minister Celso Amorin sharply criticized the United States, saying that the 2003 invasion of Iraq demonstrated that the "blind faith in intelligence reports tailored to justify political goals must be rejected."
"We must ban once and for all the use of force inconsistent with international law," Amorin told the General Assembly, adding that all international disputes should be peacefully resolved through dialogue.
The Bush administration did not seek authorization from the U.N. Security Council for the invasion, which would have legitimized the action under international law.
On Wednesday, European Union foreign policy chief Catherine Ashton, Secretary of State Hillary Rodham Clinton and the foreign ministers of Britain, China, France, Germany and Russia met to try to find a solution to the long-running dispute over Iran's nuclear ambitions. They urged Iran to come to the table for a new round of talks, and said it remained essential for Iran to prove its nuclear program is peaceful.
The U.S. and key Western allies fear Iran could try to process its low enriched uranium into highly enriched uranium to make an atomic weapon. Iran insists its nuclear program is purely peaceful, aimed solely at producing nuclear energy.
Iran has defied four rounds of increasingly restrictive economic sanctions aimed at compelling Tehran to prove it is not building a nuclear weapons program. Iran denies it is trying to build a nuclear weapon.
Talks with Tehran reached a stalemate last October, after Iranian officials tried to renegotiate an agreement to ship most of its low enriched uranium out of the country, to be turned into fuel for a research reactor.
In their meeting on Wednesday, Clinton and the other ministers said they still want to engage with Iran on a fuel swap for its research reactor. They backed the readiness of U.N. nuclear agency chief, Yukio Amano, to convene a meeting.
"We look forward to Iran's positive and constructive participation in this dialogue," they said.
On the anti-poverty summit's last day, nations pledged more than $40 billion to battle needless deaths among poor mothers and their children. But the struggling world economy, particularly in the United States, raises deep concerns that the cash won't be forthcoming. Leaders exhorted financial donors to fulfill their aid commitments.
"The crisis is no excuse for letting up our efforts, but underscores the need for actions," Ban said as he wrapped up the three-day Millennium Development Goals summit.
Associated Press Writers Slobodan Lekic, Eileen Powell and Anita Snow contributed to this report from the United Nations.