"We can't confirm its authenticity," the official said, speaking on the condition of anonymity. "It's not clear when it was done."
In the tape aired on the Arab television station Al-Jazeera Friday, the voice purporting to be Saddam called on Iraqis to help the resistance against the U.S.-led occupation.
The recording apparently confirms the widespread view in Iraq that Saddam is not only still alive but that he is at least indirectly behind the continuing attacks on American troops, reports CBS News Correspondent Mark Phillips.
"No to surrender and no to cooperation and we thank God for everything," said the tape, which the voice said was recorded on June 14.
The White House played down the tape's significance, reports CBS News Senior White House Correspondent John Roberts.
White House spokesman Ari Fleischer said it doesn't matter if it really is Saddam's voice or not.
"Regardless if he is dead or alive the mission in terms of getting rid of the regime has been achieved," he said.
CBS News Consultant Raymond Tanter agrees it doesn't matter, but for a different reason.
"All you have to do is make it appear that Saddam is somewhere in the picture and that fuels the resistance," he said.
"I relay to you good news," the voice says. "Jihad (holy war) cells and brigades have been formed."
"The reference to 'holy war' is a way of Saddam wrapping the Islamic flag around his own struggle to make him look like he's not only a nationalist but also he's a religious figure," Tanter said.
The voice also urged Iraqis to not aid coalition forces in their attempts to hunt down former Iraqi leaders.
"I call upon you to protect these heroic fighters and not give the invaders any information about them or their whereabouts during their operations," the voice said.
"There is resistance and I know you are hearing about this. Not a day passes without them (suffering) losses in our great land thanks to our great mujahedeen. The coming days will, God willing, be days of hardship and trouble for the infidel invaders."
The mujahadeen "are the young men who had come into Syria from Iraq, and they are fueling the resistance along with Saddam's regime, said Tanter.
Those who know Saddam's voice said it sounded like his.
"We (the regime) fulfilled our obligations to you and sacrificed what we had to, except our values, which are based on our deep faith and honor. We did not stab our people or our nation in the back."
Explaining why the regime fell so fast, the voice said: "We refused to hold onto power if that meant submitting to the American threats." The voice added that the previous government preferred to give up power than become a puppet state.
"They wanted to occupy us without a fight and destroy our pride," he said.
Reviews of such tapes by the American intelligence community typically include a technical analysis aimed at matching the voice to known recordings of Saddam. That process can take days.
Experts on Saddam also listen for specific references in the language that would suggest when the message was recorded.
At the height of the war, some U.S. intelligence analysts concluded that many of Saddam's messages were prerecorded before the fighting.
Hard evidence on Saddam's whereabouts and status has been lacking in the weeks since the major fighting ended. But U.S. intelligence analysts believe he is alive and most likely still in Iraq.
"The CIA will do its usual assessments," although they haven't had an opportunity to do it yet, White House press secretary Ari Fleischer said Friday when asked about this.
"We don't know if he's dead or alive," he said of Saddam. "Regardless, he's out of power. Regardless there's an award out" on him, Fleischer said, noting the U.S. offer of $25 million for information leading to the capture of the ousted Iraqi leader.
Al-Jazeera's chief editor Ibrahim Hilal, contacted in Doha, Qatar, said the tape was delivered to Al-Jazeera via telephone on Friday.
"Someone called us and played back the tape for us and we recorded it. It ran for over 20 minutes, but only 10 minutes are newsworthy. We don't know the source, or where the call came from. We have no reason to doubt its authenticity," he said.
The tape was the first purported to be from Saddam since one received May 5 by a reporter for the Sydney Morning Herald, who received a 14-minute audiotape from two men in Baghdad. In that tape, Saddam also claimed to be speaking from Iraq and called on citizens to oust American occupiers.
The voice on that tape noted some Iraqis had celebrated Saddam's 66th birthday on April 28.