VATICAN CITY — Easter Sunday Mass in St. Peter’s Square, the Catholic Church’s most joyous celebration, began with a senior cardinal defending Pope Benedict XVI from what he called “petty gossip” and hailing him for “unfailing” leadership and courage.

But the pontiff himself ignored accusations that he perpetuated a climate of cover-up for pedophile priests, even as sex abuse scandals threatened to overshadow his papacy.

The ringing tribute by Cardinal Angelo Sodano, dean of the College of Cardinals, at the start of a Mass attended by tens of thousands, marked an unusual departure from the Vatican’s Easter rituals, infusing the tradition-steeped religious ceremony with an air of a papal pep rally.

Sodano’s praise for Benedict as well as the church’s 400,000 priests worldwide cranked up a vigorous campaign by the Holy See to counter what it calls a “vile” smear operation orchestrated by anti-Vatican media aimed at weakening the papacy and its moral authority.

The pontiff and many bishops have been assailed by accusations from victims of clergy sexual abuse that Benedict helped shape and perpetuate a climate of cover-up toward the crimes against children in parishes, schools, orphanages and other church-run institutions.

Victims and their advocates are demanding that Benedict take personal responsibility.

Yet, Sodano insisted, on Easter the faithful came to “rally close around you, successor to (St.) Peter, bishop of Rome, the unfailing rock of the holy church” amid the joy of Easter.

“We are deeply grateful to you for the strength of spirit and apostolic courage with which you announce the Gospel,” said Sodano, who sought to assure Benedict that the scandals were not costing him credibility among his flock.

“Holy Father, on your side are the people of God, who do not allow themselves to be influenced by the petty gossip of the moment, by the trials which sometimes buffet the community of believers,” Sodano said.

Dressed in gold robes and shielded from a cool drizzle by a canopy, Benedict looked weary during much of the Easter Sunday ceremony, the highlight of a heavy Holy Week schedule. But as he listened intently to Sodano’s paean, a smile broke across the pope’s face, and when the cardinal finished speaking, Benedict rose from his chair in front of the altar to embrace him.

The cardinal also rushed to the defense of all the Catholic priests who “generously serve the people of God, in parishes, recreation centers, schools, hospitals and many other places, as well as in the missions in the most remote parts of the world.”

In early evening, the pope, who turns 83 on April 16, was to fly by helicopter to the papal retreat in Castel Gandolfo, a lakeside town in the Alban Hills south of Rome, where he will greet pilgrims in the palace courtyard today.