Pope Francis, drawing to a close his three-country tour of South America, on Sunday urged tens of thousands of youths in Paraguay to look after their less fortunate peers and fight for a dignified life filled with hope and strength.

"They wrote a speech for me to give you. But speeches are boring," the Argentine pontiff said to loud cheers. "Make a mess, but then also help to tidy it up. A mess which gives us a free heart, a mess which gives us solidarity, a mess which gives us hope."

It was not the first time Francis has called on young people to shake things up, repeating a mantra he voiced in Brazil in 2013 when he urged youngsters to demand a more outward-looking Catholic Church.