Pope Francis has been under pressure to address the sexual abuse crisis faced by the Church over recent years
Pope Francis has made changes to the way the Roman Catholic Church deals with cases of the sexual abuse of minors, by abolishing the rule of "pontifical secrecy" that covers them.
New papal documents lift the obligation of silence on those who report abuse or say they have been victims.
Church leaders called for the rule's abolition at a February Vatican summit.
Information in abuse cases should still be treated with "security, integrity and confidentiality", the Pope said.
He instructed Vatican officials to comply with civil laws and assist civil judicial authorities in investigating such cases.
The Pope has also changed the Vatican's definition of child pornography, increasing the age of the subject from 14 or under to 18 or under.
Archbishop of Malta Charles Scicluna called the move an "epochal decision that removes obstacles and impediments", telling Vatican news that "the question of transparency now is being implemented at the highest level".
The Church has been rocked by thousands of reports of sexual abuse by priests and accusations of cover-ups by senior clergy around the world.
Pope Francis has been under serious pressure to provide leadership and generate workable solutions to the crisis which has engulfed the Church over recent years.
- Pope orders clergy to report sex abuse
- Child sexual abuse and the Catholic Church: What you need to know
- Francis condemns child sex abuse and cover-ups
Pontifical secrecy is a rule of confidentiality which protects sensitive information regarding the governance of the Church, similar to the "classified" or "confidential" status used in companies or civil governments, the Catholic news agency says.
In the new instruction, Pope Francis said the pontifical secret would also no longer bind those working in offices of the Roman Curia to confidentiality on other offences if committed in conjunction with child abuse or child pornography.
Witnesses, alleged victims, and the person who files the report are also not bound to obligations of silence, the agency says.
Pope Benedict XVI had decreed in 2001 that these cases must be dealt with under "pontifical secret", the highest form of secrecy in the Church, the Associated Press news agency reports.
The Vatican had long insisted that such confidentiality was necessary to protect the privacy of the victim, the reputation of the accused and the integrity of the canonical process, it adds.
On his 83rd birthday, Pope Francis has responded to a long-standing complaint from survivors by announcing that any testimony gathered by the Church in relation to cases of sexual violence, the abuse of minors and child pornography will now be made available to state authorities.
In the past, the Church has been accused of using secrecy laws as a justification for not reporting cases of abuse. The consequence of breaching the pontifical secret was excommunication from the Church, so there was little incentive to be open to state authorities. That prohibition has now been abolished.
It is the latest attempt by the Roman Catholic Church to address the scourge of clerical abuse that has manifested itself across continents and in a range of religious institutions.
The Pope's troubleshooter on sexual abuse, Archbishop Charles Scicluna of Malta, has added to Tuesday's announcement saying that if it receives a specific request from a state authority, then the Church will now co-operate.
