Numerous victims were on respirators and were suffocated or burned in the smoke and flames when the blaze at eastern Baghdad's Ibn al-Khatib hospital started with an explosion caused by "a fault in the storage of oxygen cylinders", medical sources said.
The interior ministry said 82 people were killed and 110 people injured.
Patients' relatives scrambled during the blaze to save their loved ones.
The blaze spread quickly across multiple floors in the middle of the night, as dozens of relatives were at the bedsides of the 30 patients in the hospital's intensive care unit where the most severe Covid-19 cases are treated, a medical source said.
President Barham Salih described the tragedy as a "wound for the whole nation", while Prime Minister Mustafa al-Kadhimi announced an investigation, declared three days of national mourning and suspended top health officials.
These issues were raised in a 2017 public report on the Iraqi health sector, exhumed overnight in the wake of the fire by the country's human rights commission.
Many ambulances were rushing towards the hospital, ferrying away those hurt by the fire, a Reuters photographer nearby said.
Several dead in fire at Baghdad hospital for Covid-19 patients
Local and hospital officials have already been suspended over the fire and are being questioned, but they are only scapegoats, angry social media users say.
He also fired the director of Ibh al-Khatib Hospital and its director of engineering and maintenance, according to a statement from the Health Ministry and his office. Daily virus cases now average around 8000, the highest since Iraq began recording infection rates early a year ago. The cabinet suspended the health minister, Hasan al-Tamimi, and ordered an investigation of him and key hospital officials responsible for overseeing safety measures.
Although Iraq has received numerous vaccines, through government purchases and foreign donations, demand for the shots remains sluggish.
"Showing pain and sympathy with our martyrs and injured sons is not enough without strenuous accountability for the negligent, and without conducting a comprehensive and serious review", he said.
"Negligence in such matters is not a mistake, but a crime for which all negligent parties must bear responsibility", al-Kadhimi said after a security meeting Sunday. The prime minister also gave authorities 24 hours to give the results of their probe.
The Special Representative calls for stronger protection measures to ensure that such a disaster can not reoccur.
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