Two of Saddam Hussein’s most senior former aides have been hanged in Iraq, their deaths triggering an outcry and accusations of foul play as authorities admitted that one of the pair was decapitated as he fell from the gallows – an image captured by official footage of the executions.

Hooded and wearing orange boiler suits, Barzan Ibrahim al-Tikriti, Saddam’s half-brother, and Awad Ahmed al-Bandar, the former head of the revolutionary court, were executed in the early hours of Monday. Barzan, who served as the former dictator’s intelligence chief, has his head torn off by the noose during the hanging, leading to suggestions that the hangman had misjudged the length of rope needed to carry out the penalty.

Officials admitted the decapitation but denied any malice in the action, insisting there was no "violation of procedure", nor none of the rowdiness or illicit film-making that marked Saddam’s execution. However, official footage was taken of the execution, showing the pair apparently trembling in fear seconds before they meet their ends and showing Barzan's decapitated body lying on the floor. Authorities said they did not intend to release the film to the public.

Basem Ridha al-Husseini, an advisor to Prime Minister Nouri al-Maliki, described the decapitation as an "act of God" but denied that it had resulted due to error, saying that while those present were "kind of shocked", it was an eventuality that sometimes happened at executions.

"We put the head next to the body and it will be given to the families with the body," he said. We are negotiating with the families as we speak and hope it will be dealt with soon."

He said the pair had worn orange boiler suits with the words ‘justice’ on the back and were, in contrast to Saddam, hooded. Video footage shows the two standing side-by-side on what appears to be the same gallows where Saddam was hanged two weeks ago.

"They were read the order of the execution and were asked if they had wills. They said no. They were asked where their bodies were to be buried and if they wanted to pray. They did not," he said.

"Nothing went wrong. Unlike last time around. We made the witnesses sign a document for the Iraqi government acknowledging there would be no repeat of the ethnic abuse or insults to the convicts whatsoever. Everything was quiet."

He confirmed that no senior government officials were present, unlike at Saddam's execution. "We chose a totally new set of folks to prevent any controversial issues," he said.

Government officials said that the men were hanged together on a double scaffold, with 14 officials present including a representative of the ministry of information, judges and prosecution, a doctor and a prison official. They were sent to the gallows at 2.15am and were hanged at 3am.

Across the Arab world there was outrage about the botched hanging, which comes amidst international condemnation about the manner of Saddam’s own execution, after mobile phone footage showed the ex-President being taunted and insulted moments before his death.

"This execution is part of the revenge campaign going on in Iraq," said Zaid al-Boudani, a shopkeeper in the Yemei capital Sanaa. "The way his head was ripped off shows revenge and hatred."

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