The determination was made after a technical analysis by agency experts, who matched the voice to previous recordings of the al Qaeda leader, said CIA officials, speaking on the condition of anonymity. The message aired Saturday on the al-Jazeera television network.
Because of some timely references in the tape, CIA analysts interpret it to mean bin Laden was alive during the last six months. In particular, officials noted bin Laden's reference to the government of former Palestinian Prime Minister Mahmoud Abbas, who was appointed in April and resigned Sept. 6.
That reference means it was recorded since his appointment. Because it doesn't note Abbas' resignation, the message is taken by some to mean it was recorded before then, but CIA officials said that isn't certain.
U.S. intelligence officials have noted that some tape releases have been preludes to attacks. In an April 7 tape, a speaker believed to be bin Laden exhorted Muslims to rise up against Saudi Arabia and calls for suicide attacks against U.S. and British interests. Suicide bombers struck Western housing compounds in the Saudi capital on May 12.
The last message purportedly from bin Laden aired on Sept. 10 and was regarded as a propaganda ploy by al Qaeda, aimed at capitalizing on the second anniversary of the Sept. 11 attacks. That message included video of bin Laden on a mountain hike, but it was unclear when either the video or accompanying audio was recorded.
The speaker in the latest message warned Iraqis against cooperating with U.S. forces and urged youth in neighboring nations to join a jihad, or holy war, against the Americans.
"We reserve the right to respond at the appropriate time and place against all the countries participating in this unjust war, particularly Britain, Spain, Australia, Poland, Japan and Italy," bin Laden said.
"The Islamic countries who participate will not be exempt, especially the Gulf countries, most prominent among them is Kuwait, the launching base for infantry troops of the crusaders," he said.
The speaker held back a sob when addressing the Iraqi people, telling them he shares their concerns and saluting them on their jihad.
"God knows if I could find a way to your field, I wouldn't stall," the speaker said. "You my brother fighters in Iraq ... I tell you: You are God's soldiers and the arrows of Islam, and the first line of defense for this (Muslim) nation today ... so don't (fail) the Muslims today."
The speaker said this is his second message to the Iraqi people. In February, an audiotaped message believed to be from bin Laden urged Iraqis to carry out suicide attacks against Americans and draw U.S. troops into combat in Iraqi cities.
The Qatar-based satellite station Al-Jazeera received the recording Saturday from a "trusted source" who called and offered the audiotape, news editor Ibrahim Hilal said.