Pope Francis has said that sexual pleasure is "a gift from God" that should be "disciplined with patience."

He also warned against pornography, which he said brought "satisfaction without relationship" and could lead to addiction.

His Vatican address was part of a series of sermons on vices and virtues, focused on what the Pope called "the demon of lust".

It followed criticism by conservative Catholics of his new head of doctrine.

Cardinal Victor Manuel Fernández, who was appointed last July, came under fire for a book he wrote and published in the late 1990s entitled Mystical Passion: Spirituality and Sensuality.

The book, which is now out of print, discussed human sexuality and provided detailed descriptions of male and female experiences during orgasms. Speaking to Catholic online publication Crux, Cardinal Fernández said he wrote the book when he was still young and he "certainly would not" write it now.

Conservative commentators have called the book "perverse", with one saying it showed Cardinal Fernández was "unfit" to be prefect of the Dicastery for the Doctrine of the Faith.

The Pope had already tackled the vice of gluttony last week and there was no suggestion that his sermon on lust during Wednesday's general audience was related to criticism of the cardinal.

He said that lust "devastates relationships between people", adding that "daily news is enough to document this reality".

"How many relationships that started out in the best way have later become toxic relationships?" he asked.

This is not the first time Pope Francis or Cardinal Fernández have drawn the ire of conservative members of the Catholic community.

In December, Cardinal Fernández introduced a text, later approved by Pope Francis, detailing guidelines allowing priests to bless same-sex couples relationships that were still considered sinful.

Although Cardinal Fernández did emphasise that the stance did not validate the status of same-sex couples in the eyes of the Catholic Church, for many conservatives the damage was done.

Cardinal Gerhard Müller, who was the Church's head of doctrine under Pope Benedict XVI, firmly denounced the Vatican's document. In a lengthy response posted online, Cardinal Müller said that a priest blessing a homosexual union would be committing a "sacrilegious and blasphemous act".

"According to the criterion of this type of blessings, one could even bless an abortion clinic or a mafia group," Cardinal Müller said.

Prelates around the world also released statements condemning the decision, including American conservatives, who have long been vocal in opposing the Pope's plans for reforming the Catholic Church.

Tensions reached a nadir when the Pope evicted outspoken critic US Cardinal Raymond Burke from his Vatican apartment and revoked his salary.