Three Catholic bishops are currently under investigation over allegations of child abuse and one has already been convicted, Pope Francis has said.

Speaking as he returned to Rome after a historic three-day visit to the Holy Land, the pontiff called for a “zero-tolerance” approach to sex abuse within the church.

He also criticised “a global economic system that is centred on money, rather than the human person”.

Not for the first time, Francis’s remarks showed that the Argentine ‘Pope From Afar’ is not just a spiritual leader, he is also a shrewd and informed socio-political analyst.

Asked about the sex abuse question, the pope revealed that three bishops are currently under investigation.

“One has already been convicted and the punishment needs to be decided. There will be no preferential treatment when it comes to child abuse,” the pope said during a press conference on his plane to Rome.

“When a priest commits abuse, he betrays the Lord’s body. A priest must guide children towards sainthood. And the child trusts him. But instead, he abuses him or her.

“This is very serious. It’s like celebrating a black Mass! And you create a problem that will stay with (the victim) for all of his or her life.

“Next week, I will say Mass with some abuse victims in St Martha’s House. Then I will hold a meeting with them. A zero-tolerance approach needs to to be adopted with regards to this issue.”

Asked about his pilgrimage to the Holy Land, which was marked by gestures such as stopping at the Israel-Palestine dividing wall and above all by the invitation he extended to both presidents Peres and Abbas to come to Rome to pray with him, the pope said:

“The most genuine gestures are those which are made spontaneously. I had thought something could be done but none of the concrete gestures I made was conceived that way.

“Some things, like the invitation to the two presidents we had thought of doing there, during the visit, but there were lots of logistical problems. But in the end, the invitation was accepted and I hope the meeting will go well.

“My gestures are not pre-planned, I just do what comes to me spontaneously. As for that Vatican meeting, let me just say that the purpose will be to pray not meditate. The two presidents and I will only meet to pray but I believe that prayer is important and to do this helps. Then they will go home. There will be a rabbi, a Muslim and me.”

Asked about the rise of euro-scepticism as evidenced by last weekend’s elections, the pope said that whilst he was no economic expert, it was obvious that it was the result of an “inhumane economic system”.

“We have a global economic system that is centred on money, rather than the human person,” he said.

“In order to keep going, this system discards things. It discards children, the elderly and the young.

“I think unemployment among Italy’s young is 40 per cent, in Spain it’s 50 per cent, in Andalusia, 60 per cent.

“There is an entire generation of people who are not studying or working. This culture of waste is very serious. It is an inhumane economic system. As I said in (papal exhortation) Evangelii Gaudium, this economic system kills.”

Talking about another long debated church issue, namely the obligatory celibacy of the priesthood, the Pope again suggested that this is one item of Catholic Church teaching that could change, saying:

On the plane, the Pope also dealt with the question of communion for the remarried and divorced, pointing out that next October’s Synod On The Family will touch on other issues.

“Each case needs to be looked at separately. I would like to return to something Benedict XVI said on three occasions: the procedures for the annulment of marriage must be looked into, the faith with which a person enters marriage must also be examined and we also need to make it clear that the divorced are not excommunicated. So often they are treated as though they have been excommunicated.”

In other remarks, the Pope confirmed that, even if things are moving slowly, he is “happy” about the process of curia reform, pointing out that the “economic” reforms relative to institutions such as the Vatican Bank are key to the reform process.

The Pope also confirmed that his next two foreign trips will be to South Korea in August and to Sri Lanka and the Philippines next January.

He acknowledged that his predecessor, Benedict XVI, by resigning in February 2013, had set a precedent that may well be copied by future popes.

“I believe that if a bishop of Rome feels he is losing his strength, he must ask himself the same questions Pope Benedict XVI did.”