Pope Francis on Monday released a letter addressing recent revelations of a decades-long clerical sexual abuse scandal in the US, in which he said that the outcry of victims was more powerful than all the measures meant to silence them.

The pontiff said in his missive addressed "to the people of God" that no effort must be spared to prevent future cases of abuse and cover-ups, less than a week after a grand jury in the state of Pennsylvania released a report detailing the systematic rape of children by clergymen in six dioceses over a period of at least 70 years, reports Efe news.

More than 300 Catholic priests were allegedly involved in these abuses and many high-ranking ecclesiastical officials were knowingly complicit in the crimes.

"I acknowledge once more the suffering endured by many minors due to sexual abuse, the abuse of power and the abuse of conscience perpetrated by a significant number of clerics and consecrated persons," Francis said.

"The heart-wrenching pain of these victims, which cries out to heaven, was long ignored, kept quiet or silenced," he added.

"The pain of the victims and their families is also our pain, and so it is urgent that we once more reaffirm our commitment to ensure the protection of minors and of vulnerable adults."

Other than the US, sexual abuse scandals are rapidly consuming the church in several countries.

In Australia, a bishop has been found guilty of covering up sexual abuse.

In Chile, the Pope was forced to recant his dismissal of an abuse scandal involving a prominent priest and bishops accused of covering up his crimes.