By Philip Pullella
VATICAN CITY (Reuters) - Tens of thousands of faithful backed up for blocks at the Vatican on Tuesday, undergoing the strictest security checks in living memory as Pope Francis began Holy Year with a call to set aside "fear and dread".
Francis officially started the year-long religious event, also known as Jubilee, by opening the usually bricked up Holy Door of St. Peter's Basilica, following a Mass.
Holy Year has long been expected to draw millions to Rome but is now opening in the immediate aftermath of attacks in Paris and California.
From early in the morning, police checked pilgrims, reporters, diplomats and even priests entering the area starting several blocks from St. Peter's Square.
Some underwent two body and bag searches as they made their way forward.
"The risk of terrorism will never be zero, we cannot provide absolute security, but we are working to attain the level of security that people rightly ask for," Rome police chief Franco Gabrielli said.
In his homily at the Mass, Francis urged the faithful to have courage in their spiritual and daily lives: "Let us set aside all fear and dread, for these do not befit men and women who are loved. Instead, let us experience the joy of encountering that grace which transforms all things," he said.
During the year-long celebrations, one of the most important events in the 1.2 billion-member Roman Catholic Church, faithful make pilgrimages to Rome and other religious sites around the world.
This is only the 29th Holy Year in the Church since the tradition started more than 700 years ago.
A frail looking former Pope Benedict, 88, made one of his few appearances since his shock resignation in 2013. Benedict, who lives in seclusion in the Vatican, embraced Francis before the door.
Holy Years normally take place every 25 years unless a pope decrees an extraordinary one to bring attention to a particular need or topic. The next Holy Year had been scheduled for 2025 before Francis, 78, decided to call a special one on the theme of mercy, a major part of his push for a less judgmental and more inclusive Church.
NO-GO ZONE
The airspace over most of Rome was closed and transport of petrol, gas, weapons, explosives and fireworks was banned. A no-go zone was instituted for vehicles around the Vatican and rubbish bins sealed or removed.
"This security was necessary. It worked very well and it was worth it because we feel safe," said Corrado De Gioia, who came to Rome from Treviso in northern Italy.
Soldiers augmented regular police for a total security force of around 3,000, making the area around the Vatican sometimes seem more like one where a demonstration was expected instead of a religious event
Some were unnerved by the show of force.
"Regarding the security, it made me afraid. Those who come here as pilgrims meet the soldiers wearing machine guns, it's scary, you feel threatened," said Italian tourist Daniela Santi.
Hotels association Federalberghi said bookings were down about 20 percent in the Rome area, with many cancellations, and shop owners complained of a fall in sales.
"The Paris attacks have caused a lot of uneasiness," said Vincenzo Modica, who owns a souvenir shop near the Vatican.
(Additional reporting by Crispian Balmer and Eleanor Biles, Editing by Editing by Jeremy Gaunt)