Baghdad - "The tyrant has fallen," a witness shouted after Saddam Hussein dropped through the trap door of the gallows, his neck broken in an instant by the rope moments after exchanging sectarian taunts with onlookers.

Grainy footage of the execution, apparently shot on a mobile phone by a witness who was standing below looking up at the gallows, was circulating widely on the Internet on Sunday, a day after Saddam was hanged for crimes against humanity.

As the hangmen prepare him for his final moment, some of those invited to attend standing below the platform taunted the former president, who was executed on Saturday before dawn.

One man shouts "Moqtada, Moqtada, Moqtada," a reference to cleric Moqtada al-Sadr, who heads a powerful Shi'ite political movement and a militia blamed by Washington and Sunni Arabs for running death squads targeting Saddam's Sunni Arab minority.

Saddam, the noose around his neck, appears to smile and shoot back: "Is this what you call manhood?"

Another onlooker, despite pleas from another for witnesses to observe the proprieties, yells: "Go to hell!" and Saddam, seemingly accusing his enemies of destroying the nation he once led, replies: "The hell that is Iraq?"

The sound was muffled and at times indistinct, leading some who initially heard low-quality versions of the video to conclude Saddam had made rather different comments.

Another voice can be heard shouting "Long live Mohammed Bakr al-Sadr," referring to a relative of Moqtada al-Sadr killed in the 1980s.

Though Sadr's movement is a major force in the coalition government of Shi'ite Prime Minister Nuri al-Maliki, the outspoken comments by his supporters in the execution chamber may fuel charges by Saddam's defense lawyers and his supporters in Iraq and the wider Arab world that the process has been "victors' justice."

The video, lasting about two-and-a-half minutes, shows Saddam drop through the trap door while still intoning the Muslim profession of faith. He was abruptly cut off in the second verse: "I bear witness that Mohammad..."

After he falls, the cry "The tyrant has fallen" is audible over shouting and other comments that could not be made out.

The video bore out witness comments that the 69-year-old former leader, who looked calm and composed as he stood on the gallows in an official video broadcast on Saturday, had shouted angry political slogans while masked guards were bringing him into the execution chamber once used by his own feared intelligence services.

Toward the end of the film, Saddam's body is shown swinging, eyes partly open and the neck bent almost at right angles to one side. The film is punctuated by flashes, apparently as witnesses took photographs.