The Qatar-based satellite broadcaster Al-Jazeera broke into programming with the announcer saying it was about to play a purported Saddam tape in which he denied his involvement in the Friday attack that killed at least 85 people, including revered Shiite cleric Ayatollah Mohammad Baqir al-Hakim.
"Maybe many of you have heard the hiss of the snakes, the servants of the occupiers, how they accused us without any evidence of killing of al-Hakim," the voice said.
Al-Jazeera clearly did not broadcast the tape in its entirety.
The voice said Saddam was the leader of all Iraqi people, suggesting he would not launch an attack on any particular ethnic or religious group - Shiites included.
"Saddam Hussein is not the leader of a minority or a group within a group. He is the leader of the great Iraqi people," the voice said.
During his rule, Saddam drew most of his support from Sunni Muslims, a minority that oppressed the Shiite majority for decades.
The last audiotape purportedly from Saddam was broadcast Aug. 1. On that tape, the speaker said the former leader would "at any moment" defeat the American occupation forces and return to power.
That tape also said looters of government property should not worry about retribution from Saddam and instead should join the guerrilla war and become "a loaded rifle in the face of the invading foreigner."
Quoting the Quran, the voice said:
"Ye believers, if a corrupt person brought you news, check it well before accusing arbitrarily. Otherwise, you will regret your accusation."
Many in Najaf have laid blame for the bombing with Saddam loyalists. While police officials have said they have 19 suspects in custody, many of them foreigners and some with links to al Qaeda, Osama bin Laden's terror group.
It was not possible to immediately determine if the tape was authentic.
Vowing revenge and beating their chests, more than 300,000 Shiites marched Sunday behind the rose-strewn coffin of a beloved cleric assassinated in a car bombing. Najaf leaders asked the FBI for help investigating the blast, which killed 125 people.
Iraqi police said the bomb that exploded after noon prayers Friday at the vast Imam Ali mosque contained the equivalent of 1,650 pounds of TNT.
The explosion was so powerful it was impossible to recover much of Ayatollah Mohammad Baqir al-Hakim remains.
His coffin may be empty, but as CBS News Correspondent David Hawkins, his followers are full of desire for revenge.
They chanted "down with the occupation" and waved banners saying "Bush and Saddam will not humiliate us."
The call for the FBI to join the investigation represented a shift after U.S. authorities had taken a hands-off approach - out of deference to the sacredness of the mosque, which houses the tomb of the Prophet Muhammad's son-in-law, Ali.
In other recent developments:
A key figure in the U.S.-picked Governing Council wrote in a Washington Post op-ed column Sunday that the United States needed to include Iraqis in their own security. "America must reach out to its friends and allies in Iraq to share the burden of defeating Saddam once and for all," wrote Ahmad Chalabi, leader of the Iraqi National Congress. "You have the firepower and mobility, we have the local knowledge and intelligence. Only if we work as true partners will we achieve the victory that is so vital to both our countries," he wrote.
A U.S. military official says American forces have had no access to those in Iraqi police custody, but said he had heard numbers ranging from nine to 19.
Police said there were similarities between the mosque bombing and the recent attacks at the Jordanian Embassy and United Nations.
Iraqi police said the bomb at the Imam Ali Shrine - the burial place of the son-in-law of the Prophet Muhammad - was made from the same type of materials used in the previous bomb attacks.
The bombing in Najaf added urgency to U.S. plans to create a 7,500-strong Iraqi militia that would eventually take over civil defense duties in the country's cities. Gen. John Abizaid, the head of U.S. Central Command, announced plans to create the new militia, called the Iraqi Civil Defense Corps, on July 21.