VATICAN CITY -- Pope Francis presided over solemn Good Friday services amid heightened security at Rome's Colosseum for the Via Crucis procession and a new communications controversy at home. Italian police, carabinieri and soldiers were on alert, with Holy Week coinciding with a spate of arrests of suspected Islamic extremists around Italy and warnings from law enforcement about the return of foreign fighters from Iraq and Syria.

At the start of the most solemn period of the Catholic Church calendar, Francis lay prostrate in front of the altar in St. Peter's Basilica before the chant-filled Good Friday evening service got underway.

Later Friday, Francis travels to the Colosseum to preside over the Way of the Cross procession re-enacting Christ's crucifixion -- the seminal event in Christianity leading to Christ's resurrection celebrated on Easter Sunday.

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The solemn commemorations coincide with a new communications controversy in the Vatican over the pope's reported assertion -- at the height of Holy Week -- that hell doesn't exist. The Vatican hasn't denied Francis' comments to the La Repubblica newspaper, saying only that the journalist reconstructed a conversation.

It was the fifth time in five years that Francis has spoken to Repubblica's founder, Eugenio Scalfari, a devout atheist who admits he doesn't record or take notes during interviews.

Nearly every time a Francis interview has appeared on Repubblica's front page, the Vatican press office has insisted the pope's words weren't necessarily accurate, without denying them outright. That has prompted questions about why the pope continually lets himself be quoted by Scalfari.

Spokesman Greg Burke didn't respond Friday when asked whether the pope believes in the existence of hell or not. Francis has in the past spoke frequently about the devil and hell.

The doubts, however, have enraged Catholic conservatives, who have lost their patience with a pope who seems to care less about doctrine than dialogue, especially with atheists and people of other faiths.