Dozens gathered in one of the monastery's churches that have been rebuilt in stone six years after the Islamic State group (IS) pulverised them, in a city home to one of the world's oldest Christian communities.

It is the latest sign of a slow return to normality in Iraq's second city.

Mosul was left in ruins after three years of jihadist occupation which ended in 2017 when an Iraqi force backed by US-led coalition air strikes pushed them out.

"We have old memories in this monastery," said Maan Bassem Ajjaj, 53, a civil servant who moved to Arbil, capital of the neighbouring autonomous region of Kurdistan, to escape the jihadists.

"My son and daughter were baptised here," he said. "Each Friday, Mosul's Christian families would come here."

The US Department of State funded the project, which also had support from a Christian non-governmental group, L'Oeuvre d'Orient, according to Samer Yohanna, a superior of the Antonian order of Chaldean monks.

He told AFP that the jihadists destroyed 70 percent of the monastery the year after they occupied Mosul in 2014 and declared the establishment of an Islamic "caliphate".

The IS onslaught forced hundreds of thousands of Christians in Nineveh province surrounding Mosul 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 that toppled dictator Saddam Hussein.

On a visit to Iraq in March, Pope Francis prayed outside another ruined church, one of at least 14 which IS destroyed in Nineveh.

Although the churches have been repaired, other parts of the centuries-old monastery still need restoration.

"You can see walls that are still standing but are weak and which need to be reinforced," Yohanna said.

Chaldean Bishop Thabet Habib, from the Al-Qosh diocese, said further work was needed so the entire monastery "can regain its splendour".

Last month, Mosul's Muslim community celebrated with a ceremony to mark the birthday of the Prophet Mohammed at the historic Al-Nuri mosque, which too was severely damaged by IS but is also being restored.