A British-born Italian teenager has become the Catholic Church’s first millennial Saint.

Carlo Acutis, who was just 15 when he died from leukaemia in 2006, has been canonised in a service watched by thousands of young people at St Peter’s Square in Rome.

He became known as ‘God’s Influencer’ after using his computer skills to spread the word and he is regarded as a pioneer of the church’s evangelising efforts in the digital age.

Pier Giorgio Frassatti was canonised at the same time – he died in 1925 at the age of 24. He was known for his devotion to serving the poor and carrying out acts of charity while spreading his faith to his friends.

During the open-air Mass Pope Leo said both young men had created "masterpieces" out of their lives by dedicating them to God.

"The greatest risk in life is to waste it outside of God's plan," he said in his homily.

And he added that the new Saints "are an invitation to all of us, especially young people, not to squander our lives, but to direct them upwards and make them masterpieces".

It’s the first time Pope Leo has presided over such a ceremony and it was also attended by Carlo’s mother Antonia Salzano who was pictured filing past the pontiff. She has previously described how her son’s faith was evident from a young age, even though the family wasn’t particularly religious. She said he used his pocket money to help the homeless in Milan where the family lived and always stood up for children who were being bullied.

She also said she had come to faith through her son.

The Catholic church hopes the canonisation of the young Saints will help engage younger generations and inspire new believers.