Pope Francis has condemned the “atrocities” of child sexual abuse and Catholic church leaders who covered up the crimes, saying “we showed no care for the little ones; we abandoned them”.

In a rare 2000-word letter issued by the Vatican to the world’s 1.2 billion Catholics on Monday, the Pope called for an end to the “culture of death” in the Church and acknowledges the Church’s role in failing to act sooner on sexual abuse.

The strongly worded letter comes less than a week after former Adelaide archbishop Philip Wilson was sentenced to home detention for covering up historic child abuse by a Catholic priest.

“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,” the Pope wrote in his first letter addressed to the entire Catholic population on the topic of sex abuse.

“Looking back to the past, no effort to beg pardon and to seek to repair the harm done will ever be sufficient. Looking ahead to the future, no effort must be spared to create a culture able to prevent such situations from happening, but also to prevent the possibility of their being covered up and perpetuated.”

“With shame and repentance, we acknowledge as an ecclesial community that we were not where we should have been, that we did not act in a timely manner, realising the magnitude and the gravity of the damage done to so many lives,” he said.

Pope Francis begged forgiveness for the “heart-wrenching pain” suffered by victims and said lay Catholics must be involved in any effort to root out abuse and cover-up.

He blasted the self-referential clerical culture that has been blamed for the abuse crisis, with church leaders more concerned for their reputation than the safety of children.

“We showed no care for the little ones; we abandoned them,” he said.

The Pope’s message comes in response to new revelations in the US of decades of misconduct by the Catholic Church, and ahead of Francis’ trip this weekend to Ireland that is expected to be dominated by the abuse crisis.

Last month, Pope Francis accepted the resignation of Cardinal Theodore McCarrick, a high-ranking Vatican official from Washington over abuse accusations against him.

-with agencies