A video has been published of Shehzad Tanweer, from Leeds, who killed seven people with a suicide bomb on the London Underground on 7 July 2005.
The video also showed a map of central London, the scene of carnage on 7 July when a total of 52 people died.
Tanweer said the 7 July bombings would herald a string of attacks which would not stop "until you pull your forces out of Afghanistan and Iraq".
Also shown in the footage is what appears to be the mixing of chemicals for use in attacks.
An explosion is also shown in the video, in which Tanweer accuses the UK government of causing oppression in various countries.
If the video is confirmed as genuine, it adds growing credence to the possibility that al-Qaeda was behind the London bombings.
Ayman al-Zawahri, al-Qaeda's second in command, also appeared on the video, praising Tanweer and mentioning his enthusiasm for PE and sport.