Pope Francis on Wednesday called for Catholics around the world to give up trolling on social media for Lent, saying believers should observe a fast not just of food but of online insults in order for them to get nearer to God in the run-up to Easter.

Pope Francis puts ashes on the forehead of Cardinal Jozef Tomko in the Santa Sabina Basilica during the Ash Wednesday Mass opening Lent, the forty-day period of abstinence and deprivation for Christians before Holy Week and Easter. Credit:AP

The Pope issued his appeal for more online decorum in an address to 12,000 people in St Peter's Square for his general audience on Ash Wednesday, the start of the 40-day period that leads up to Easter.

Lent, he said in remarks that were apparently off-the-cuff, "is a time to give up useless words, gossip, rumours, tittle-tattle and speak to the Lord on first name terms".

"We live in an atmosphere polluted by too much verbal violence, too many offensive and harmful words, which are amplified by the internet," he said.