As John Paul II mania grips Rome ahead of Sunday's ceremony that will put the late pope on the path to sainthood, thousands of young devotees are flocking to the city to celebrate their hero.

"We were born during John Paul II's pontificate, attended his audiences and spent World Youth Days with him," said Massimo Manzolillo, a member of the Papa Boys Association, a fan club set up in 2005 after his death.

"He was our friend. A friend of ours is being beatified, it's an incredible, wonderful thing," he said. "I wouldn't miss this for the world."

Armed with sleeping bags, "blessed" John Paul II T-shirts and an irrepressible enthusiasm, up to 13,000 Papa Boys are making their way by the busload from across Italy to St. Peter's Square for the beatification.

Dismissing critics who have accused the Vatican of unjustly fast-tracking the process, the youngsters have no doubt their mentor merits sainthood and has more than the two miracles up his sleeve necessary to achieve it.

"We have hundreds of people calling us up and telling us about the pope's miracles," said Daniele Venturi, head of Italy's Papa Boys.

"I know of at least 700 children who have been named after John Paul II because they were miracle babies, born to mothers who couldn't conceive and whose prayers for help were then answered," he added.

Those arriving in Rome in time for a vigil on Saturday will be cramming into hostels near the Vatican or bunking for free in a youth camp set up by the city council a nearby seaside town.

"We're coming for the vigil and will stay late into the night before heading to the Vatican to camp out and wait for dawn," said 29-year old Manzolillo, who will be travelling from Naples along with five busloads of Papa Boys.

"We're bringing sleeping bags but I don't think any of us will sleep. We don't want to miss out on the atmosphere, the emotion. And we need to make sure we're first in line for the best seats for the ceremony on Sunday," he added.

To commemorate the occasion, the association has published "Ciao Karol!" (Goodbye Karol), a collection of 1,500 messages which were written by children in 2005 when the pope died and were left for him in St. Peter's Square.

The letters, postcards and scraps of poems written in Italian and dozens of other languages and illustrated by colourful drawings and scribbles thank John Paul II for being a "great Pope, great father, great friend, great angel."

"The letter that moved me the most - where the son of a mafia boss asks John Paul II forgiveness for all the murders he has witnessed - will appear in the next edition. The 15,000 first copies have already sold out," Venturi said.

"The raw emotion comes through in every letter. John Paul II touched so many lives, in one way or another. And we will be there this weekend to show him how much he meant to us," he said.