Pope Benedict XVI said on the first anniversary of his election as pontiff Wednesday that he could not do the job alone, and he asked for continued prayers to be the "gentle and firm" pastor of the Roman Catholic Church.

A visibly moved Benedict told an estimated 50,000 people gathered in St. Peter's Square that his election came as a complete surprise to him, saying the cardinals had elected "my poor person" to succeed "the great Pope John Paul II."

"I always knew I couldn't do this job, this mission alone," he said. "Thank you from the heart to all those who in various ways are near me or follow me spiritually with affection and prayers from afar.

"To each one of you, I ask you to continue to support me praying to God to let me be his gentle and firm pastor of his church," he said.

Benedict was the oldest pope elected in 275 years and the first German one in nearly 1,000 years when he was chosen, at age 78, to succeed John Paul on April 19, 2005.

As John Paul's right-hand man, he had been a favorite going into the vote and was selected in the fastest conclave in a century. Just about 24 hours after the voting began, white smoke curled from the Sistine Chapel chimney at 5:50 p.m. to announce a new pope had been selected.

Still, Benedict's election immediately posed questions about the future of the church since the former Cardinal Joseph Ratzinger was such a polarizing figure. Some said he might further drive away more liberal-minded Catholics, who had hoped for a change from the hard-line John Paul.

The Vatican this week reported that more than 4 million people had attended Benedict's Masses, audiences and prayer appearances in the past year, including the estimated 50,000 present at Wednesday's audience.

Benedict opened the session by recalling his election, saying it was "absolutely unexpected and surprising" that the cardinals had chosen him.

"How time flies," he said, recalling his first comments to the public after the vote, in which he walked out onto the loggia of St. Peter's Basilica and told the faithful that the cardinals had elected a "simple, humble worker in the vineyard of the Lord" to be the next pope.

Benedict was interrupted by applause a half-dozen times during his brief remarks. Many of the church groups attending Wednesday's audience were from his native Germany.

Benedict, who celebrated his 79th birthday Sunday, flew to Rome for the audience from the papal retreat in Castel Gandolfo, where he has been resting after a busy Easter week. He is expected to return to Rome on Friday to attend a concert at the capital's major music venue in honor of his first year.

His next major commitment is his May 25-28 trip to John Paul's native Poland, where he is expected to visit the late pontiff's hometown of Wadowice as well as the Auschwitz concentration camp.