The video first appeared on an al-Qaida Web site Sunday, and features Ayman al-Zawahiri sitting in front of a professional television set, the BBC reported.
"No matter how much the gigantic propaganda machine in America tries to deceive the people, the reality is stronger and worse than all the deceptions," al-Zawahiri said from an undisclosed location.
Al-Zawahri also claimed British troops were being forced to "flee" the south of the country where they turned over security to Iraqi forces Sunday.
He issued a form of death sentence for Sunni Muslims helping coalition troops, calling for the mujahedin al-Qaida fighters to "throw out the bribe-taking collaborators from among their ranks, those who sold out their faith and fight under the banner of the cross.
"They must expose them to the Muslim world," al-Zawahiri said.
In turn, a British military spokesman in Basra told Sky News the statement was nothing more than propaganda by an organization "that does not have a foothold in this region."