Pope Francis prayed Sunday for "victims of war" outside a centuries-old church in Iraq's Mosul, where the Islamic State group ravaged one of the world's oldest Christian communities until the jihadists' defeat three years ago.

With the crumbling stone walls of the Al-Tahera (Immaculate Conception) Church behind him, Pope Francis made a plea for Christians in Iraq and the Middle East to stay in their homelands.

Pope Francis, travelling under tight security in Iraq, will lead a prayer 'for the victims of the war' against IS in the city of Mosul
Pope Francis, travelling under tight security in Iraq, will lead a prayer 'for the victims of the war' against IS in the city of Mosul AFP / Vincenzo PINTO

The 84-year-old pontiff said the "tragic" exodus of Christians from war-scarred Iraq and the wider region "does incalculable harm not just to the individuals and communities concerned, but also to the society they leave behind".

The IS onslaught forced hundreds of thousands of Christians in northern Iraq's Nineveh province to flee. Iraq's Christian population has shrunk to fewer than 400,000 from around 1.5 million before the US-led invasion of 2003.

Rows of seats were set out in the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul's Old City ahead of Pope Francis' visit
Rows of seats were set out in the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul's Old City ahead of Pope Francis' visit AFP / Zaid AL-OBEIDI

The faithful had gathered on Sunday in the courtyard of the Al-Tahera Church, whose roof collapsed during fighting against IS in 2017.

It is one of the oldest of at least 14 churches in Nineveh province that were destroyed by IS.

Youths unfurled a poster welcoming Francis next to the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul
Youths unfurled a poster welcoming Francis next to the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul AFP / Zaid AL-OBEIDI

Boutros Chito, a Catholic priest in Mosul, said the pope's visit could change the way people think about his city, the ancient centre of which still lies in ruins.

"Pope Francis will announce to the whole world that we are the people of peace, a civilisation of love," Chito told AFP.

Pope Francis greets Iraqis dressed in traditional outfits upon his arrival at Arbil airport in Kurdish Iraq on Sunday
Pope Francis greets Iraqis dressed in traditional outfits upon his arrival at Arbil airport in Kurdish Iraq on Sunday AFP / Safin HAMED

The heaviest deployment of security forces yet has been mobilised to protect Francis on what is perhaps the riskiest day of his historic trip to Iraq, where state forces are still hunting IS sleeper cells.

Youths unfurled a poster welcoming Francis next to the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul
Youths unfurled a poster welcoming Francis next to the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul AFP / Zaid AL-OBEIDI

Pope Francis's trip to Iraq as a "pilgrim of peace" aims to reassure the country's dwindling Christian community and to expand his dialogue with other religions.

Rows of seats were set out in the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul's Old City ahead of Pope Francis' visit
Rows of seats were set out in the ruins of the Syriac Catholic Church of the Immaculate Conception in Mosul's Old City ahead of Pope Francis' visit AFP / Zaid AL-OBEIDI

On Saturday, the leader of the world's 1.3 billion Catholics met Iraq's top Shiite Muslim cleric, the reclusive Grand Ayatollah Ali Sistani, who agreed that Iraq's Christians should be able to live in "peace".

"We believers cannot be silent when terrorism abuses religion," Francis said at an interfaith service in the ancient site of Ur later that morning.

Watching from afar as IS swept across Nineveh in 2014, Pope Francis said at the time he was ready to come and meet the displaced and other victims of war in a show of solidarity.

Pope Francis's trip to Iraq as a "pilgrim of peace" aims to reassure the country's dwindling Christian community and to expand his dialogue with other religions
Pope Francis's trip to Iraq as a "pilgrim of peace" aims to reassure the country's dwindling Christian community and to expand his dialogue with other religions AFP / Vincenzo PINTO

Seven years later, he is visiting both Mosul and Qaraqosh, one of Iraq's oldest Christian towns whose residents still speak a dialect of Syriac, the language spoken by Jesus Christ.

It, too, was largely destroyed when IS rampaged through the area, but its residents have trickled back since 2017 and slowly worked at rebuilding their hometown.

"This very important visit will boost our morale after years of difficulties, problems and wars," said Father George Jahoula in Qaraqosh.

To honour the pope, local artisans wove a two-metre (6.5-foot) prayer shawl, or stole, with the "Our Father" and "Hail Mary" prayers carefully hand-stitched in golden thread in Syriac.

It was given to Francis on his first day in Iraq on Friday.

Francis landed early on Sunday at the airport in the Kurdish regional capital of Arbil, which was targeted just a few weeks ago by a volley of rockets that killed two people.

He held a brief meeting with regional president Nechirvan Barzani and his cousin, the prime minister Masrour Barzani.

Many thousands of troops and police have been deployed as the pope has criss-crossed Iraq, taking planes, helicopters and armoured convoys to cover more than 1,400 kilometres (870 miles) in-country.

The other major challenge is the Covid-19 pandemic, with Iraq gripped by a second wave bringing around 5,000 new cases per day.

Authorities have imposed a nationwide lockdown -- ostensibly to keep cases down but also to help control movements of crowds during the pope's high-profile visit.

While Francis has been vaccinated, Iraq has only just begun a modest inoculation campaign and there are fears that the crowds gathering to see him could lead to super-spreader events.

The biggest event yet will be on Sunday afternoon, when several thousand people will gather at Arbil's Franso Hariri stadium for the Pope's last mass in Iraq.

Arbil has been a relative haven of stability and a place of refuge for many Christians who fled IS.