The Iraqi government launched an inquiry on Monday into how guards filmed and taunted Saddam Hussein on the gallows, turning his execution into a televised spectacle that has inflamed sectarian anger.
A senior Iraqi official told the agency that the US ambassador tried to persuade Prime Minister Nuri al-Maliki not to rush into hanging the former president just four days after his appeal was turned down, urging the government to wait another two weeks.
News of the ousted strongman's death on Saturday and of his treatment by officials of the Shi'ite-led government was blamed by one witness for sparking a prison riot among mainly Sunni Arab inmates at a jail near the northern city of Mosul.
An adviser to Maliki, Sami al-Askari, said: "There were a few guards who shouted slogans that were inappropriate and that's now the subject of a government investigation."
The government released video showing the hangman talking to a composed Saddam as he placed the noose round his neck.
But mobile phone footage on the web showed guards shouting "Go to hell!", chanting the name of a Shi'ite militia leader and exchanging insults with Saddam before he fell through the trap in mid-prayer and his body swung, broken-necked, on the rope.
Saddam's exiled eldest daughter and even some residents of Dujail, the Shi'ite town whose sufferings led to his conviction for crimes against humanity, joined mourning rituals for him, most of these concentrated among Sunni Arabs in Saddam's home region north of Baghdad where he was buried on Sunday.
Mourners continued to arrive at his native village of Awja, near Tikrit. His daughter Raghd, who helped finance his defense from her strictly supervised exile in Jordan, joined several hundred people in the capital Amman in a show of solidarity.
Iraqi troops and police rushed to Mosul's Padush prison to put down a riot after visitors broke news of Saddam's treatment.
The governor said seven guards and three prisoners were injured although a visitor reported gunfire and the death of an inmate.
There has been no significant repeat of the series of car bombings that killed over 70 people in Shi'ite neighborhoods on Saturday within hours of the dawn execution, but the government and US forces are on alert for the kind of sectarian violence that has pitched Iraq toward civil war since Saddam's overthrow.
Interior ministry data showed the number of Iraqi civilians killed in political violence hit a new record high in December after a big leap the previous month.
The statistics, almost certain to be an underestimate, showed 12,320 civilians were killed in 2006 in what officials termed "terrorist" violence.
The Interior Ministry ordered the closure of another Iraqi television channel, Sharkiya, accusing it of fomenting hatred.
The channel, owned by a London-based businessman who was once an official under Saddam, continued broadcasting from Dubai.
The government has taken similar measures against several channels, all with perceived Sunni leanings.
President Bush plans to unveil a new strategy this month after the 3,000th soldier to die in Iraq since the March 2003 invasion was killed just before New Year.
At least 112 Americans died in December, the deadliest month for them in more than two years as they struggled to contain the bloodshed.
Two US soldiers died in an explosion on Sunday northeast of Baghdad. US forces said they killed six insurgents in a raid on a suspected Al-Qaeda safe house in Baghdad.
While Saddam's sentencing and then death brought muted responses from most Sunnis, many have been particularly angered by video showing supporters of Shi'ite cleric and militia leader Moqtada al-Sadr chanting "Moqtada, Moqtada, Moqtada!" at him. "Is this what you call manhood?" Saddam told them in reply.
Maliki adviser Askari said the government would look into how guards in the execution chamber, once used by Saddam's own feared secret police, had smuggled in a mobile phone camera.
Askari said: "They have damaged the image of the Sadrists. That should not have happened. Before we went into the room we had an agreement that no one should bring a mobile phone."
US forces had declined to give Saddam to Iraqis for fear of abuses of his prisoner's rights. They only agreed to hand him over for execution hours before the unannounced hanging.
A government official involved in the talks said, on condition of anonymity, that US ambassador Zalmay Khalilzad had urged Maliki to wait another two weeks, until after the long Muslim festival of Eid al-Adha, and had insisted on a variety of documents including approval from Iraq's Kurdish president.
"The Americans wanted to delay the execution by 15 days because they weren't keen on having him executed straight away," he said.
"But ... the prime minister's office provided all the documents they asked for and the Americans changed their minds when they saw the prime minister was very insistent."
A US embassy spokesman declined immediate comment.
Senior Iraqi officials have forecast a limited New Year offensive by US-led forces against Sadr's Mehdi Army.
"There will be limited and targeted operations against members of the Mehdi Army," one senior Shi'ite official said.