At the main hospital in the predominantly Christian town east of Mosul, an AFP photographer saw ambulances arriving with sirens blaring and dozens of people gathering in the courtyard to donate blood.

Others could be seen gathering in front of the open doors of a refrigerated truck loaded with black body bags.

Citing a "preliminary tally", Iraq's official INA news agency reported that health authorities in Nineveh province had "counted 100 dead and more than 150 injured in the fire at a marriage hall in Hamdaniyah", as the town is also known.

The casualty toll was confirmed to AFP by health ministry spokesman Saif al-Badr.

Badr said most of the injured were being treated for burns or oxygen deprivation, adding that there had also been crowd crushes in the packed reception hall.

The Iraqi Red Crescent said it had recorded more than 450 casualties but was unable to provide a breakdown of how many had died.

In a statement, civil defence authorities reported the presence of prefabricated panels inside the event hall that were "highly flammable and contravened safety standards".

The danger was compounded by the "release of toxic gases linked to the combustion of the panels", which contained plastic.

"The fire caused some parts of the ceiling to fall due to the use of highly flammable, low-cost construction materials," the statement said, with "preliminary information" suggesting fireworks were to blame for the blaze.

- 'We were suffocating' -

Wedding guest Rania Waad, who sustained a burn to her hand, said that as the bride and groom "were slow dancing, the fireworks started to climb to the ceiling (and) the whole hall went up in flames".

"We couldn't see anything," the 17-year-old said, choking back sobs. "We were suffocating, we didn't know how to get out."

Emergency crews were seen sifting through the charred remains of the event hall early Wednesday, inspecting the scene by flashlight.

In a brief statement, Prime Minister Mohamed Shia al-Sudani called on the health and interior ministers to "mobilise all rescue efforts" to help the victims of the fire.

The health ministry said "medical aid trucks" had been dispatched to the area from Baghdad and other provinces, adding that its teams in Nineveh had been mobilised to care for the injured.

Safety standards in Iraq's construction sector are often disregarded, and the country, whose infrastructure is in disrepair after decades of conflict, is often the scene of fatal fires and accidents.

In July 2021, a fire in the Covid unit of a hospital in southern Iraq killed more than 60 people.

And in April of the same year, exploding oxygen tanks triggered a fire at a hospital in Baghdad -- also dedicated to Covid patients -- that killed more than 80 people.

Like many Christian towns in the Nineveh Plains, northeast of Mosul, Qaraqosh was ransacked by jihadists of the Islamic State group after they entered the town in 2014.

Qaraqosh and its churches were slowly rebuilt after the group's ouster in 2017, and Pope Francis visited the town in March 2021.