His message will be watched closely by angry Catholics from Boston to Berlin to see if he acknowledges only the abuse itself -- or the decades of Vatican-approved cover-ups too.

Throughout the Catholic world, the church is only starting to come to terms with the scale of child abuse permitted in many of its parishes and schools throughout the 20th century.

The tide of scandal has surged from Canada and Australia in the 1980s, to Ireland in the 1990s, reaching the United States at the turn of the century and finally the pope's German homeland this week.

Commentators and victims' rights activists agree that, to begin mending the church's battered image, the message to Ireland -- his first pastoral letter on child abuse in the church -- must break his silence on the pivotal role of the Catholic hierarchy in shielding pedophiles from prosecution. Including under the pope's own watch in Munich decades ago.

"Is it not time for Pope Benedict XVI himself to acknowledge his share of responsibility, instead of whining about a campaign against his person? No other person in the church has had to deal with so many cases of abuse crossing his desk," said the Rev. Hans Kung, a Swiss priest and dissident Catholic theologian.

"Honesty demands that Joseph Ratzinger himself, the man who for decades has been principally responsible for the worldwide cover-up, at last pronounce his own mea culpa," Rev. Kung said.

The pope, who served as archbishop of Munich from 1977 to 1982, has yet to speak about hundreds of abuse cases surfacing in Germany, particularly in his former archdiocese, since January.

The cases include the Rev. Peter Hullerman, who was already suspected of abusing boys in the western Germany city of Essen when Cardinal Ratzinger approved his transfer to Munich for private treatment in 1980. Hullerman was permitted to maintain contact with children, was convicted of abusing a boy in 1986 and was discovered last week still to be working as a priest in contact with children.

Dirk Taenzler, director of the Federation for German Catholic Youth, said his members were appalled by the revelations of past abuse in church-run schools and choirs -- and wondered why the pope had yet to address his fellow Germans as he is about to do with the Irish.