Next month's unprecedented Vatican summit on the protection of children should give all bishops concrete guidelines for preventing and reporting abuse, the Catholic Church's chief spokesman has said.

"For the Holy Father (Pope Francis), it is fundamental that when the bishops who come to Rome return to their countries, to their dioceses, they are aware of the rules to apply," the acting head of the Vatican press office, Alessandro Gisotti told journalists.

"Thus they can accomplish the necessary steps to prevent abuse, protect victims and ensure that no case be covered up or concealed," Mr Gisotti said.

The summit has been called by Pope Francis for 21-24 February.

The Catholic Church has had to contend with a wave of scandals involving priests sexually abusing children which have engulfed it in many countries including Ireland, Chile, the United States and Australia.

Last month Pope Francis promised to "render justice to minors", saying the February meeting was "meant to be a further step in the church's efforts to shed full light on the facts and to alleviate the wounds caused by such crimes".

The February meeting is expected to attract 180 participants, including the presidents of 113 national hierarchies (bishops' conferences) from around the world.

The Irish church will be represented by Archbishop Eamon Martin, the Primate of All Ireland.

Earlier this week, a former papal advisor on child safeguarding, Marie Collins, called on the Pope Francis to use the summit to seek agreement for global zero tolerance and full transparency on clerical sex abuse.

Speaking in Dublin, Ms Collins said he must ensure, through practical measures, that children are protected from abuse in the church regardless of where they live.

She told the gathering, hosted by the reform-minded We Are Church Ireland organisation, that limited reforms had been imposed on the Irish, American and some other national churches by public outrage at horrific revelations of abuse and its institutional cover-up.

She also lamented that most of the global church has not seen improvements.

Ms Collins, who resigned in 2017 from Pope Francis' Commission for the Protection of Minors, was among the six abuse survivor-advocates who met the pontiff in Dublin last August.

She recalled that she questioned his decision to drop a proposed Vatican tribunal to try bishops who conceal abuse.

The change of mind on the commission's proposal prompted Ms Collins to resign from the body dealing a body-blow to Pope Francis' earliest initiative to counter the abuse crisis.

Ms Collins, who was sexually abused in childhood by a priest in the Dublin diocese, said a universal church rule of zero tolerance and full transparency on clerical sex abuse would be in tune with Catholicism's tradition of universal doctrine and canon law.