Pope Francis vowed on Sunday to keep Iraq in his heart, as he concluded the largest mass and final public event of a historic trip meant to encourage the country's dwindling Christian community and deepen interfaith dialogue.

The Pontiff celebrated among thousands of smiling worshippers in a sports stadium in the Kurdistan region's capital Erbil, after visiting Christian survivors of the Daesh terror group's reign of terror.

The 84-year-old was driven in his white, windowless "pope-mobile" into the stadium, where jubilant worshippers sat socially distanced on white chairs spread out on the greens.

Others stood, craning their necks to catch a glimpse of Francis, in the stands ringing the Franso Hariri Stadium, named after an Iraqi Christian politician who was assassinated by extremists 20 years ago.

In concluding the mass, the Pope vowed to keep Iraq in his heart even when he returns to the Vatican on Monday.

"In my time among you, I have heard voices of sorrow and loss, but also voices of hope and consolation," he said.

"Now the time draws near for my return to Rome. Yet, Iraq will always remain with me, in my heart."

The faithful wore hats featuring pictures of Francis, and face-masks to protect them from COVID, as a second wave has driven up cases to around 5,000 new infections per day in Iraq.

The stadium seats around 20,000, but large swathes of the stands were empty after authorities had trimmed down the allowed attendance in recent days.

"It's a special trip, also because of the conditions," said Matteo Bruni, the Vatican's spokesman, who described the visit to Iraq as "a gesture of love for this land its people".

Iraq’s Christian population has shrunk to fewer than 400,000, from around 1.5 million before the US-led invasion of 2003.

Erbil has been a place of refuge for many Christians who fled violence over the years, including Daesh extremists’ 2014 onslaught and ensuing reign of terror.

The heaviest security deployment yet is protecting Francis in northern Iraq on what is perhaps the riskiest day of his historic trip.

The city was targeted just weeks ago by a deadly rocket attack, the latest in a series of strikes blamed on pro-Iranian forces.

‘The most beautiful day’

The visit to the north came the day after 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 Iraq’s Christians should be able to live in "peace”.

It also embodies a cause close to the Pope’s heart: Reaching out to Iraq’s traumatised Christian community.

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