"Yes, he passed away and his body is now in the hospital freezer," said Saad Maan, head of the ministry's media relations department.

A medical source at the hospital confirmed to AFP that Hashemi had suffered "a hail of bullet wounds in several body parts."

The investigator assigned to the killing told AFP that Hashemi, 47, walked out of his home in east Baghdad and was getting into his car when three gunmen on two motorcycles fired at him from metres away.

Hashemi was wounded and ducked behind his car, but the gunmen approached and shot him four times in the head at close range, the investigator said.

Hashemi was an authoritative voice on Sunni jihadist factions including the Islamic State group, but was also frequently consulted by media and foreign governments on domestic Iraqi politics and Shiite armed groups.

He had come out strongly in favour of the popular protests that erupted across Baghdad and Iraq's Shiite-majority south in October, which had slammed the government as corrupt, inefficient and beholden to neighbouring Iran.

More than 500 people lost their lives in protest-related violence, including several prominent activists who were gunned down in Baghdad, Basra in the south and other cities.

But high-profile political killings have otherwise been rare in recent years.

"Cowards killed my friend and one of the brightest researchers in Iraq, Hisham al-Hashemi. I am shocked," wrote Harith Hasan, who was an academic researcher before becoming an advisor to Iraq's current premier.