Catholic clergy will no longer be able to cite papal secrecy in sexual abuse cases after Pope Francis changed the rules, the Vatican said on Tuesday. 

Pope Francis' instructions referenced two articles of Vatican law that refer to sexual abuse cases, specifying that "the pontifical secret does not apply to accusations, trials and decisions" involving such offences. 

So-called pontifical secrecy is a rule of confidentiality designed to protect sensitive information related to the governance of the Roman Catholic Church - including diplomatic correspondence, personnel issues and crimes.

The Church has been rocked by thousands of reports of sexual abuse by priests and accusations of cover-ups by senior clergy.

Last May, the pontiff passed a landmark measure to oblige those who know about sex abuse to report it to their superiors, in a move which could bring new cases to light.

In Tuesday's statement, the Argentine pontiff spelt out further that "the person who files the report, the person who alleges to have been harmed and the witnesses shall not be bound by any obligation of silence with regard to matters involving the case".

Archbishop of Malta Charles Scicluna called Pope Francis' 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 decision, he said facilitate communication with victims and survivors.

It would also facilitate the cooperation between the Church, the state and the statutory authorities in combating crime waged against minors, Mgr Scicluna told Times of Malta.