The explosion was caused by "a fault in the storage of oxygen cylinders", the medical sources said, adding that several dozen people had also been wounded.

Videos on social media showed firefighters trying to extinguish flames at Ibn al-Khatib hospital on the southeastern outskirts of the Iraqi capital as patients and their relatives tried to flee the building.

The civil defense told Iraqi state news they "rescued 90 people out of 120 patients and their relatives" at the scene, but would not give the exact number of dead and wounded.

On Wednesday, the number of Covid-19 cases surpassed one million in Iraq, with the health ministry recording a total of 1,025,288 cases of the disease and 15,217 deaths since the first infections were reported in the country in February 2020.

The ministry has said it carries out around 40,000 tests daily from a population of 40 million.

Iraq's hospitals have been worn down by decades of conflict and poor investment, with shortages in medicines and hospital beds.

Those patients who can often prefer to source oxygen tanks for treatment at home, rather than go to overcrowded and run-down hospitals.