An Iraqi firefighter works at the site of a suicide car bombing claimed by the Islamic State group on Jul 3, 2016 in Baghdad s central Karrada district. AP
The bombing was one of the world's deadliest after the September 11, 2001 attacks on the United States.
At least 323 people were killed in the car bombing that sparked raging fires in Baghdad's Karrada shopping area early on July 3, 2016 as it teemed with people ahead of the Eid al-Fitr festival ending the Muslim holy month of Ramadan.
Prime Minister Mohammed Shia al-Sudani, during a meeting with victims' families, informed them "the rightful punishment of death sentence was carried out against three key criminals found guilty of their involvement in the terrorist bombing", his office said in a statement.
It was one of the deadliest attacks to ever hit Iraq.
Police Major General Talib Khalil Rahi said at the time that the bomber's minibus had been loaded with plastic explosives and ammonium nitrate.
The initial blast killed a limited number of people, but flames spread and trapped people inside shopping centres which lacked emergency exits, Rahi told a news conference a few days later.
The raging fires made it difficult to identify the dead.
Interior Minister Mohammed Ghabban resigned in the wake of the blast.
IS had overrun large areas north and west of Baghdad in 2014, but by the time of the Karrada blast Iraqi forces had regained significant territory from the jihadists, who hit back against civilians in response.
Iraq's government declared victory against IS in late 2017 after a military campaign backed by a United States-led military coalition.
In October 2021 Iraq announced the arrest outside the country of the person it said was the main suspect behind the Karrada blast. Then-prime minister Mustafa al-Kadhemi said Ghazwan Alzawbaee was "the primary culprit" in that attack "and many others."
A government source told AFP that Alzawbaee was among those put to death.
The statement from Sudani's office, however, did not name those executed or say when they were sentenced. It said the executions were carried out Sunday night and Monday morning.
The United Nations estimated in a report in March that IS still has "5,000 to 7,000 members and supporters" across Iraq and neighbouring Syria, "roughly half of whom are fighters".
IS cells continue to target security forces and civilians in both countries but the UN report said IS had been much depleted by "sustained counter-terrorism operations" on both sides of the border.
Over several years, Iraqi courts have handed down hundreds of death sentences as well as life prison terms under the penal code for membership in "a terrorist group".
Iraqi courts also issue the death penalty for intentional homicide.
In 2022 Iraq executed more than 11 people, fewer than in the United States, and sentenced more than 41 to death, according to a report by Amnesty International.