MOSUL, (Iraq): Muslim and Christian residents in the ruined Iraqi city of Mosul told Pope Francis of their lives under brutal Islamic State rule on Sunday as the pontiff blessed their vow to rise up from ashes and told them that "fraternity is more durable than fratricide."

Francis, on a historic first visit by a pope to Iraq, visited the northern city to encourage the healing of sectarian wounds and to pray for the dead of any religion.

The 84-year-old pope saw ruins of houses and churches in a square that was the old town's thriving centre before Mosul was occupied by Islamic State from 2014 to 2017. He sat surrounded by skeletons of buildings, dangling concrete staircases, and cratered ancient churches, most too dangerous to enter.

"Together we say no to fundamentalism. No to sectarianism and no to corruption," the Chaldean archbishop of Mosul, Najeeb Michaeel, told the pope.

Much of the old city was destroyed in 2017 during the bloody battle by Iraqi forces and an international military coalition to drive out Islamic State.

Francis, who flew to Mosul by helicopter, was visibly moved by the earthquake-like devastation around him. He prayed for all of the city's dead.

"How cruel it is that this country, the cradle of civilization, should have been afflicted by so barbarous a blow, with ancient places of worship destroyed and many thousands of people - Muslims, Christians, Yazidis and others - forcibly displaced or killed," he said.