A group led by al-Qaeda ally Abu Musab al-Zarqawi posted a video on an Internet site of a suicide car bombing that killed three British troops and an Iraqi.
The tape showed a car driving down a road south of Baghdad and then slowing down, allowing several other vehicles to pass, before it blew up in apparent footage of Thursday's attack.
Plumes of black smoke rose as the man behind the camera, who was taping from a distance, shouted "God is greatest." A script on the video identified the bomber as Abu Suleiman and said he had waited for civilian cars to pass before blowing up his car.
The three soldiers and an Iraqi translator were killed when the car bomber attacked their checkpoint south of Baghdad in the first suicide attack on UK forces in Iraq.
Eight other British soldiers were wounded.
The video, posted on a website often used by Islamists and carrying the logo of Al Qaeda Organization of Holy War in Iraq, also showed what it said were British troops removing the bodies and the injured as well as a helicopter airlifting them.
The troops were part of a force of about 850 British troops deployed to volatile areas southwest of Baghdad last month to free up US forces for an expected assault on the rebel-held city of Fallujah.