Prosecutor Munkith al-Faroon, who is heard appealing for order on explicit Internet video of Saturday's hanging that has inflamed sectarian passions, said on Tuesday he threatened to leave if the jeering did not stop -- and that would have halted the execution as a prosecution observer must be present by law.

"I threatened to leave," Faroon told Reuters. "They knew that if I left, the execution could not go ahead."

Many in Saddam's Sunni minority, and moderate Shi'ites and Kurds, have been angered and embarrassed by the video. In it, observers chant "Moqtada, Moqtada, Moqtada!" for Shi'ite militia leader Moqtada al-Sadr. Saddam by contrast looks dignified on the gallows and replies: "Is this what you call manhood?"

As the Iraqi government mounted an investigation into how officials smuggled in mobile phone cameras, he also challenged the accounts of the justice minister and an adviser to the prime minister who said the film was shot by a guard -- Faroon said one of two people taking video was a senior government official.

"Two officials were holding mobile phone cameras," said Faroon, who was a deputy prosecutor in the case for which Saddam was hanged and is the chief prosecutor in a second trial that will continue against his aides for genocide against the Kurds.

"One of them I know. He's a high-ranking government official," Faroon said, declining to name the man. "The other I also know by sight, though not his name. He is also senior.

"I don't know how they got their mobiles in because the Americans took all our phones, even mine which has no camera."

Faroon said he was the only prosecutor from Saddam's trial for crimes against humanity against the people of the Shi'ite town of Dujail who was present in Baghdad. The Penal Code stipulates that one prosecutor must be present at any execution.

The government released brief silent footage showing only the hangman placing the noose over Saddam's head. The illicit video shows, as well as the taunts, the former president drop through the trap and swing, broken-necked, on the rope.

U.S. forces had kept custody of Saddam since they captured him three years ago, partly over fears about his treatment by the Shi'ite Muslim majority he oppressed while in power and now the main force in Prime Minister Nuri al-Maliki's government.

Officials, witnesses and journalists attending his trial over the past year were subjected to rigorous background and security checks before entering the court and U.S. troops handed Saddam over to Iraqi guards only at the last moment on Saturday.

Americans flew him by helicopter from the Camp Cropper jail at Baghdad airport to the former secret police base in the north of the capital where he was hanged after negotiations between Maliki and the U.S. ambassador that lasted late into the night.

The Americans screened an official delegation before escorting them to the execution site.

U.S. envoy Zalmay Khalilzad urged Maliki to delay the dawn execution for two weeks, till after the long Eid al-Adha Muslim holiday, a senior Iraqi government official told Reuters. But he relented when Maliki insisted and provided an authorisation also from Iraq's Kurdish president, the official said on Monday. Reuters