The video, which was posted on whistleblowers website Wikileaks, shows footage taken by a US helicopter gunship as it fired on people in the New Baghdad surburb of the Iraqi capital on 12 July 2007. Jim Boumelha, IFJ president, said the video was evidence of "calculated, cold-blooded and horrifying violence".
He said: "The United States cannot ignore this atrocity and the killings of unarmed civilians. We insist on a completely new review of these and all the killings of journalists and media staff in the Iraq conflict. Altogether there have been 19 unexplained killings of media staff at the hands of US soldiers," he added.
"The administration of Barack Obama cannot duck its responsibility to set aside the whitewash of self-exonerating reporting by the US army. Justice requires that there is no impunity and that the US military is held to account for its actions in Iraq."
Reuters photographer Namir Noor-Eldeen and driver Saeed Chmagh were among those killed in the helicopter attack. The video shows the initial attack and then further shooting of people trying to help the wounded. A US military source confirmed to Reuters that the video was genuine. Wikileaks told a news conference in Washington that it been given the encrypted video of the attack by a military whistleblower. The video shows airborne US troops misidentifying the journalists' cameras as weapons before firing on them.
David Schlesinger, Reuters' editor-in-chief, said the video showed that the deaths of Noor-Eldeen and Chmagh were "tragic and emblematic of the extreme dangers that exist in covering war zones". Video of the incident, captured from two US Apache helicopters, was shown to Reuters editors in an off-the-record briefing in Baghdad in July 2007. They were told they would have to make a request under the US Freedom of Information Act to get copies.
The US military has told Reuters that it found weapons at the scene of the attack including AK-47 rifles and a grenade launcher. Reuters' then bureau chief in Iraq, Dean Yates, said in 2007 that his staff felt they had lost both their "little brother" and "elder brother" following the deaths of Noor-Eldeen and Chmagh. The two men, aged 22 and 40 respectively, were the sixth Reuters journalists to be killed by the US military covering the war in Iraq.
Dominic Ponsford is the editor of Press Gazette.