The Vatican updated its rules for supernatural events Friday, such as visions of Christ or the Virgin Mary, including the acknowledgement that overactive imaginations and outright "lying" risked harming the faithful.

The new norms, published by the Holy See's powerful Dicastery for the Doctrine of the Faith and approved by Pope Francis, allow for a more "prudent" interpretation of events that generally avoids declaring them outright a supernatural event.

"In certain circumstances not everything is black or white," Cardinal Victor Manuel Fernandez, who leads the dicastery, said at a press conference.

"Sometimes a possible divine reaction mixes with... human thoughts and fantasies," Fernandez added.

The history of the Catholic Church is filled with episodes of strange or unexplained phenomena involving religious statues or other objects, whether in Italy or beyond.

The new guidelines come two months after the Church said that a series of widely reported miracles attributed to a statuette of the Virgin Mary -- including making a pizza grow in size -- were false.

The rules, which represent the first update since 1978, provide more guidance to bishops who until now have been left relatively free to determine the authenticity of such visions on a case-by-case basis. 

Underscoring the complexity of the issue, only six cases of such alleged supernatural events have been "officially resolved" by the Vatican since 1950, with one taking "seventy excruciating years", the document said.

"Today, we have come to the conviction that such complicated situations, which create confusion among the faithful, should always be avoided," wrote Fernandez in the document. 

The new rules call for more collaboration between the individual dioceses and the Vatican regarding such events. Bishops' final decisions will be submitted to the dicastery for approval.

That is crucial because "sometimes the discernment may also deal with problems, such as delicts (civil offences), manipulation, damage to the unity of the Church, undue financial gain, and serious doctrinal errors that could cause scandals and undermine the credibility of the Church," said the document. 

They include believers "misled by an event attributed to a divine initiative but is merely the product of someone’s imagination" or those who have an "inclination toward lying". 

In the absence of problems, dioceses will be able to declare a "Nihil Obstat", indicating there is nothing in the phenomenon contrary to faith and morals. 

That falls short of an official declaration of its supernatural authenticity, which is generally to be avoided under the new rules unless the pope authorizes it.