A leading Catholic theologian has revealed that Pope Francis could soon relax the rules on priestly celibacy and allow Catholic priests to marry.

Leonardo Boff, from Brazil, a prominent liberation theologian who himself resigned as a priest after his liberal views put him at odds with the hierarchy, said the Brazilian bishops had explicitly asked Pope Francis to allow men who had left the ministry to marry to serve as priests again. 

Currently there are thousands of ordained priests worldwide who left the active ministry to marry. The Catholic Church makes rare exceptions to its celibacy rule. Eastern Rite priests are, like their Orthodox counterparts, allowed to be married if they married before ordination, although they cannot become bishops.

In the UK, the Catholic Church has ordained married Anglican clergy who wished to become Catholic priests after the vote to ordain women.

But in general the celibacy rule stands.

And the Catholic Church is entering a massive crisis over an international shortage of new priests and a rapidly-ageing existing priesthood.

In an interview with the German daily newspaper Kölner Stadt-Anzeiger, Boff says it is possible that married priests could be used again in pastoral care.

"This is an explicit request from the Brazilian bishops to the Pope, especially his friend, the emeritus Brazilian Cardinal Claudio Hummes.

"I heard that the Pope wanted to comply with this request – initially for an experimental phase in Brazil."

Brazil has 140 million Catholics and needs at least 100,000 priests, but there are currently just 18,000.

Boff says: "Institutionally, this is a disaster. It is no wonder that the faithful overflow with the evangelicals and Pentecostals who fill the vacuum.

"If the many thousands of married priests were to be able to exercise their office again, this would be a first step towards improving the situation."

As a former Franciscan, he says he does not personally need this change because he still exercises his priestly ministry: "I baptise, I bury, and when I go to a church without a priest, I celebrate the Mass together with the people."

He says he has never been criticised or forbidden from doing this.

"The bishops even rejoice and tell me: 'The people have a right to the Eucharist. So keep quiet!' My theological teacher, Cardinal Paulo Evaristo Arns, who died a few days ago, for example, was very open. He went so far as to bring married priests, whom he saw sitting in the bench during the Mass, to the front of the altar, and together with them celebrated the Eucharistic celebration. He often did that and said. 'You are still priests, and you will remain priests!"

Boff, who currently serves as Professor Emeritus of Ethics, Philosophy of Religion and Ecology at Rio de Janeiro State University in Brazil, resigned in 1992 after years criticising the church leadership. He has consistently backed the ordination of women and allowing priests to marry.

He made his name as a liberation theologian speaking out for the poor of Latin America.

Boff also defends in the interview Pope Francis against the criticism of senior conservative cardinals in the church including Raymond Burke.

Boff describes Burke as "the Donald Trump of the Catholic Church".

Burke and three other cardinals wrote to the Pope last year challenging his teaching after his statement in September that divorced and remarried Catholics can in "some cases" receive Holy Communion without living as "brother and sister" and without getting an annulment.

But unlike Trump, says Boff, Burke is now "in the cold in the Curia – thank God".

He condemns Burke and his fellow conservatives for attempting to correct the Pope. 

"These people actually believe they should correct the Pope. As if they were above the Pope. Such a thing is unusual, if not unprecedented in the Church's history. You can criticise the Pope, discuss it. I have done this often enough. But that Cardinals publicly accuse the Pope of spreading theological errors or even heresies, which I think is too much. This is an affront... The Pope can not be condemned, that is Church teaching."

He says Pope Francis is more interested in the survival of mankind and the future of the earth rather than preserving his own Church hierarchy.

"Both are in danger, and one must ask whether Christianity can contribute to overcoming this great crisis that threatens humanity."