A life-size mural depicting Pope Francis with a saintly halo kissing US President Donald Trump sprouting devil's horns appeared on a wall near the Vatican on Thursday, less than two weeks before they are due to meet.

The mural, which was painted on paper and pasted on to the wall during the night, was the latest work by street artists depicting the Pope to appear in Rome in recent months.

This one shows Francis, wearing a simple cross around his neck, embracing Trump, who wears a gold watch and sports a pistol in a holster. The Pope's halo is the same bright yellow colour as Trump's hair.

The caption written on the sash of the Pope's cassock reads 'The Good Forgives the Evil.' It is signed 'TVBoy,' who is believed to be Italian street artist Salvatore Benintende.

Trump and the Pope have not always seen eye to eye. The pontiff criticised the billionaire tycoon while he was running for office,  specifically over his southern border wall. 'A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian. This is not the gospel,' said the Pope. Trump hit back at the time, but it seems relations have thawed somewhat with Trump expected to stop at the Vatican as part of his first ever foreign trip as president.

'It is very provocative but not too shocking for someone coming from America,' said a tourist from Burbank, California who gave only his first name, Victor.

The mural was pasted on a wall on a street named 'Way of the Bank of Holy Spirit' across the Tiber River from the Vatican.

Francis and Trump are due to meet at the Vatican on May 24 while the president is on a tour Saudi Arabia, Israel, Italy and Belgium.

Such murals depicting the pope eventually are taken down by a special group of Rome sanitation workers known as 'The Decorum Squad'.

In the past, the squad has erased a mural depicting the Pope as a sneaky graffiti artist painting peace signs on walls and another showing him as the comic book hero Superman.

Local media have criticized the unit for removing popular art while unsightly graffiti blights many buildings.

Additional reporting by Reuters.