Sistani, 94, who met the late pontiff in 2021 in the first-ever papal visit to Iraq, said in a statement issued by his office that it was an "important milestone" in supporting interfaith dialogue and "rejecting violence and hatred".

Francis had a "special role in serving the causes of peace and tolerance, and solidarity with the oppressed and persecuted around the world", Sistani said.

After his historic trip to Iraq, Francis said his meeting with Sistani -- who is extremely reclusive and rarely grants audiences -- had been "good for my soul".

The meeting marked a landmark moment in modern religious history and for Francis's efforts to deepen interfaith dialogue. Sistani told the pope that Iraq's Christians should live in "peace".

Despite the high risks to his personal safety, Francis visited the largely-ruined city of Mosul that was ravaged by the Islamic State group until the jihadists' defeat in 2017.

By the time of Francis's visit, Iraq's Christian population had shrunk during years of violence in the country to fewer than 400,000, from around 1.5 million before the US-led invasion of 2003.

Francis prayed for the victims of war outside the ruined centuries-old Al-Tahera (Immaculate Conception) Church, where he pleaded for Christians in Iraq and the Middle East to stay in their homelands.

On Monday, Benedictus Younan Hanno, the Archbishop of the Syriac Catholic Church of Mosul, the capital of Nineveh province, home to one of the world's oldest Christian communities, called on churches to ring their bells for the deceased pope.

Iraq's Prime Minister Mohammed Shia al-Sudani mourned a pope who had "a life devoted to serving humanity."

"We recall with reverence his historic visit to Iraq... an event that laid a meaningful foundation for interfaith dialogue and promoted fraternity and compassion among people of all faiths," he said.