Pope Francis is summoning the presidents of every bishops conference around the world for a February summit to discuss preventing clergy sex abuse and protecting children.

Francis' key cardinal advisers announced the decision on Wednesday, as the latest chapter in the Catholic Church's long-running sex abuse and cover-up scandal has thrown Francis' papacy into crisis.

The February 21-24 meeting is believed to be the first of its kind, and signals a realisation at the highest levels of the church that clergy sex abuse is a global problem and not restricted to the Anglo-Saxon world, as many church leaders have long insisted.

Francis' papacy has been jolted by accusations he rehabilitated a top American cardinal from sanctions imposed by Pope Benedict XVI for having molested and harassed adult seminarians.

The Vatican hasn't responded to the accusations by Archbishop Carlo Maria Vigano, but has promised "clarifications" that presumably will come sometime after Francis' meeting Thursday with the US delegation.

The Vatican said the meeting would be headed by Cardinal Daniel DiNardo, head of the US Conference of Catholic Bishops, and also include Francis' top sex abuse adviser, Cardinal Sean O'Malley.

Di Nardo has said he wants the Pope to authorise a full-fledged Vatican investigation into ex-Cardinal Theodore McCarrick, who was removed as cardinal in July after a credible accusation that he groped a teenager.

The Vatican has known since at least 2000 that McCarrick would invite seminarians to his New Jersey beach house and into his bed.

John Paul II made him archbishop of Washington and a cardinal in 2001, presumably because Vatican officials were impressed by his fundraising prowess and considered his past homosexual activity a mere "moral lapse" and not a gross abuse of power.

DiNardo has also said recent accusations that top Vatican officials - including the current Pope - covered up for McCarrick since 2000 deserve answers.