NEW YORK — Making a plea for human rights, Pope Benedict XVI warned diplomats at the United Nations on Friday that international cooperation needed to solve urgent problems is "in crisis" because decisions rest in the hands of a few powerful nations.

The U.N. speech highlighted another active day on Benedict's first papal trip to the United States that also included the first visit by the leader of the Roman Catholic Church to an American synagogue.

Associated Press (ENLARGE)

Pope Benedict XVI addresses the U.N. General Assembly Friday.

Associated Press (ENLARGE)

Pope Benedict XVI acknowledges applause after addressing the General Assembly Friday, April 18, 2008 at the United Nations headquarters.

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In a major speech on his U.S. trip, Benedict said that respect for human rights, not violence, was the key to solving many of the world's problems.

While he didn't identify the countries that have a stranglehold on global power, the German pope — just the third pontiff to address the U.N. General Assembly — addressed long-standing Vatican concerns about the struggle to achieve world peace and the development of the poorest regions.

On the one hand, he said, collective action by the international community is needed to solve the planet's greatest challenges.

On the other, "we experience the obvious paradox of a multilateral consensus that continues to be in crisis because it is still subordinated to the decisions of a few."

The pope made no mention of the United States in his speech, though the Vatican did not support the U.S.-led invasion of Iraq in 2003, which occurred despite the Bush administration's failure to gain Security Council approval for it. At other moments on his trip, Benedict has been overtly critical of the U.S., noting how opportunity and hope have not always been available to minorities.

The pope said questions of security, development and protection of the environment require international leaders to work together in good faith, particularly when dealing with Africa and other underdeveloped areas vulnerable to "the negative effects of globalization."

Benedict also insisted that the way to peace was by insuring respect for the dignity of human beings.

"The promotion of human rights remains the most effective strategy for eliminating inequalities between countries and social groups, and increasing security," the pope said.

Those whose rights are trampled, he said, "become easy prey to the call to violence and they then become violators of peace."

By contrast, the pope said, recognition of human rights favors "conversion of heart, which then leads to a commitment to resist violence, terrorism and war."

While Benedict, a former university professor and theologian, has spoken out less on global conflicts than his predecessor, John Paul II, he too lived through the Second World War. He was drafted into the German army at war's end and later deserted.

After three days in Washington, the pope took an early morning flight from the nation's capital to New York City.

His late-afternoon stop at Park East Synagogue, a modern Orthodox congregation, was mostly symbolic — a quick visit to offer greetings as Passover approaches, exchange gifts and signal the increasingly warm relations between Catholicism and Judaism.

"May God spread his canopy of peace over all of us," Rabbi Arthur Schneier told the pope in his welcoming remarks.

"I assure you ... of my closeness at this time, as you prepare to celebrate the great deeds of the Almighty," Benedict said.

Benedict did not address atonement for clergy sex abuse in his U.N. speech, which has developed into a major theme on the trip. He has been widely expected to broach the subject Saturday when he celebrates Mass for priests, deacons and members of religious orders at St. Patrick's Cathedral in Manhattan.

Some victims' advocates are pressing for bishops to be sanctioned for their role in the scandal that has cost the U.S. church more than $2 billion.

Cardinal William Levada, an American cleric who runs the Vatican agency that enforces church doctrine, said Friday he does not know of any bishops guilty of "aiding and abetting" pedophiles, and would respond if he did. Bishops who have made mistakes, he said, largely took advice that was accepted at the time but proved wrong.

Levada said it was possible that canonical rules, or church rules, could be changed to better address the abuse scourge.

"It's possible," Levada said in a conversation with reporters. "There are some things under consideration that I'm not able to say."

Across from the U.N., several hundred supporters, many of them Hispanic, gathered behind metal police barricades as Benedict spoke.

"Benedetto!" many shouted in Spanish.

A group of New Jersey Catholics held up a banner for the German-born pope that combined German — "Willkommen Pope Benedict XVI" — and English sentiments: "You Rock!"

A small anti-pope contingent included a group calling itself Forum for Protection of Religious Pluralism. Financial consultant Padmanabh Rao, a Hindu from Woodbridge, N.J., complained that the Vatican is converting people in India to Catholicism.

Before the pontiff's speech, Benedict and Secretary-General Ban Ki-moon met alone for 15 minutes for what the Vatican called a discussion on a range of international issues. No details were given.

Later, speaking to U.N. staff members, Benedict paid tribute to 42 civilians and peacekeepers killed in 2007. He said the United Nations plays a key role in monitoring how well governments protect their citizens.

"Indeed," he said, "this is coming to be recognized as the moral basis for a government's claim to authority."