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WASHINGTON, April 15 (Reuters) - Pope Benedict arrived in Washington for his first papal visit to the United States on Tuesday after declaring himself "deeply ashamed" by a sexual abuse scandal tarnishing the Roman Catholic Church's image here.

On his flight from Rome, the pope vowed to keep pedophiles out of the priesthood. The scandal of priests sexually abusing youths broke in 2002 and has forced U.S. dioceses to pay over $2 billion in damages. Five have gone bankrupt.

The six-day visit includes a United Nations address, masses in baseball stadiums and meetings with Catholic educators and leaders of other religions, but the abuse scandal has shaken the Church so much that the German-born pope addressed it even before landing.

President George W. Bush greeted the pontiff on arrival at Andrews Air Force Base outside the U.S. capital, the first time he has gone to the airport to meet an incoming dignitary. Neither made a public statement, but onlookers sang "Happy Birthday" for Benedict, who turns 81 on Wednesday.

"We will absolutely exclude pedophiles from the sacred ministry," Benedict told reporters on his flight across the Atlantic. The Church will screen candidates for the priesthood, he said, "so that only really sound persons can be admitted."

"It is more important to have good priests than to have many priests," Benedict said.

Polls say three-quarters of U.S. Catholics approve of the pope, but just as many say they disapprove of the defensive way the Church first responded to the sexual abuse crisis.

The pontiff said he would discuss the sensitive topic of immigration with Bush, especially the way it split families and strained "the moral and social fabric" of poor countries.

"The United States has to help these countries develop," he said during the flight, so their citizens do not feel they must leave. "It is in the interest of everyone, not only these countries but of the world and particularly of the United States."

He also praised the role of faith in American public life as an example for more secularized Europe.

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White House spokeswoman Dana Perino said Bush and Benedict would probably discuss "their shared values of human rights and the importance of fighting extremism and also promoting religious tolerance" at the White House on Wednesday.

During his six-day trip, Benedict will also pray at Ground Zero, the site in New York where the World Trade Center was destroyed on Sept. 11, 2001.

A Washington Post-ABC news poll published on Tuesday showed almost three-quarters of U.S. Catholics approve of Pope Benedict but most find the Church out of touch with their views and criticize the way the sex abuse scandal was handled.

Half wanted the pope to stress traditional teachings and 45 percent preferred policies that "reflect the attitudes and lifestyles of modern Catholics."

Most Americans view the pontiff favorably , but he is not as popular as his immediate predecessor, John Paul II, a poll by the Pew Forum on Religion & Public Life showed.

Benedict said the sexual abuse scandal caused "great suffering" to the Church in the United States and also "for me personally."

"It's difficult for me to understand how it was possible that priests betrayed in this way their mission to give healing, to give the love of God to these children," he said.

Several victims of the pedophile priest scandal denounced Benedict's comments as hollow and insincere during a news conference in Boston, where the scandal erupted in 2002.

"He should be ashamed that he is not meeting with survivors and talking with us," said Robert Costello, founder of A Matter of Truth, a Boston-based organization for victims of sexual abuse by priests.

The pope, who marks the third anniversary of his election during the trip, has said he hopes the visit will lead to a spiritual renewal in America. His U.N. address on Friday will aim to highlight the need for greater peace and justice around the world.

In New York, Benedict will also make a brief stop at a synagogue to wish the Jewish community a happy Passover. (Additional reporting by Tabassum Zakaria at Andrews Air Force Base; Writing by Tom Heneghan; Editing by Patricia Zengerle)

(For more on religion, see the Reuters religion blog FaithWorld at

blogs.reuters.com/faithworld

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