Pope Francis has chastised Catholics for using their phones during Mass, saying it makes him sad to see hundreds of screens held up in prayer.

The pontiff is not known to use a mobile himself and has previously urged young believers to carry Bibles rather than iPhones.

'At a certain point the priest leading the ceremony says "lift up our hearts". He doesn't say "lift up our mobile phones to take photographs" — it's a very ugly thing,' the pontiff said at his weekly address to pilgrims in St Peter's Square, Rome.

'It's so sad when I'm celebrating Mass here or inside the Basilica and I see lots of phones held up - not just by the faithful, but also by priests and bishops! Please!'

Francis has a mixed relationship with technology, rebuking families for using phones at the dinner table while also being named the most influential tweeter in the world.

A study of the Twitter accounts of world leaders by PR firm Burson Marsteller in 2015 put Francis at the top for the third time running. With more than 19 million followers between his nine accounts, he's not the most popular but the pontiff's online musings spread the furthest.

Francis enjoys an average of 9,929 retweet per tweet from his Spanish account and 7,527 from his English one.

And while the Pope has admitted he is a tech 'dinosaur' he said the internet is a 'gift from God' and has carved out time to meet with the heads of companies such as Google and Apple.