Pope Francis has issued a stark warning against online pornography, calling it a temptation that "weakens the priestly heart."

He was speaking to priests and seminarians studying in Rome when asked how digital and social media should be best used.

"Each of you think if you've had the experience or had the temptation of digital pornography. It's a vice that so many people have, so many laymen, so many laywomen, and even priests and nuns," Pope Francis said, according to a transcript published by the Vatican on Wednesday.

"I'm not just talking about criminal pornography like child abuse, where you see live cases of abuse: that's already degeneracy. But of the more 'normal' pornography," he continued.

Pornography should be deleted from mobile phones

The 85-year-old head of the Catholic Church admitted he did not use or own a mobile phone but urged the faithful to use them to communicate better.

He cautioned against obsessively watching the news and listening to music that distracts from one's work, before broaching a more serious risk.

"The pure heart, the heart that receives Jesus every day, cannot receive this pornographic information," he said.

He advised the group to "delete such things from their mobile phones," adding that they should do so to keep temptation out of their hands.

"I tell you, this is a thing that weakens the spirit," the pope explained.

lo/sms (AFP, dpa)