One of the largest crowds ever to gather on the lawns of the White House sang an impromptu chorus of Happy Birthday to Pope Benedict XVI as the pontiff, who turned 81 today, began the first full day of a visit to the United States.

More than 9,000 guests packed the sun-drenched South Lawn as Benedict became only the second pope ever to visit the White House and the first in nearly 30 years. He received a 21-gun salute and heard Kathleen Battle, the American soprano, produce a haunting rendition of The Lord's Prayer

But, in election year, politics was never far beneath the surface and cheers rose from the crowd as President Bush, in his speech of welcome, noted the Church's prohibition of abortion.

“In a world where some evoke the name of God to justify acts of terror and murder and hate, we need your message that God is love. And embracing this love is the surest way to save man from falling prey to the teaching of fanaticism and terrorism,” Mr Bush said.

He added: ""We hear your message that all human life is sacred, that each of us is willed, that each of us is necessary."

After the welcoming ceremony, the President and the Pope were to hold a private 45-minute meeting in the Oval Office, with officials on both sides saying that neither leader was happy with US handling of immigration from Latin America, home to many of the world's Catholics.

The pontiff was expected to mute past public criticisms of the war in Iraq, but the White House said that the two men were likely to evoke the plight of Christians there with the conflict in its sixth year.

A Washington Who’s Who flocked to the White House to greet the Pope, including Dick Cheney, the Vice-President and Condoleezza Rice, Secretary of State.

On the flight from Rome to Washington yesterday, Pope Benedict broached the most sensitive issue surrounding his trip when he told reporters he felt “deeply ashamed” by the child abuse scandal that has rocked the US Catholic Church, and would “do everything possible to heal this wound".

Replying to Mr Bush's speech of welcome, Pope Benedict said that he had come as a friend of the United States. He urged Americans and their leaders to base their political and social decisions on moral principles and create a more just society.

“I come as a friend, a preacher of the Gospel and one with great respect for this vast pluralistic society,” he said in a speech that was full of praise for American society and sprinkled with references to the founding fathers, the Declaration of Independence and George Washington, the first US president.