London, (AFP)- Investigators were trying to determine whether a London suicide bomber made his posthumous "war" video in Britain or Pakistan as they probe how deeply al-Qaeda was involved in the coordinated attack.
Though his headless body lies in a London mortuary, Mohammad Siddique Khan came back to haunt investigators with a video on Thursday warning of more bombings like the one on July 7 which killed 52 rush-hour commuters.
Khan was named by police as one of the four bombers, who all died in the attack.
A man identified as Khan said on the video that he admired al-Qaeda leader Osama bin Laden and his deputy Ayman al-Zawahiri, who appeared separately in the footage aired on the al-Jazeera television channel.
"We are at war and I am a soldier," he said in a flat Yorkshire accent.
If the video were recorded in Pakistan, where Khan traveled in the months before the attack, it could point to al-Qaeda being more involved in the plot than had previously been known.
The Sunday Telegraph said British investigators were working with security services in Pakistan to find out where the video was made, possibly in Rawalpindi, a hotbed of Islamic militancy outside the capital Islamabad.
Rawalpindi is where Khalid Sheikh Mohammed, the alleged architect of the September 11 attacks on the United States, was arrested.
If it were made in the northern city of Leeds, where Khan lived, or elsewhere in Britain, it would make it more likely that Khan and his three cohorts took inspiration rather than orders from al-Qaeda, newspapers said.
The Guardian newspaper reported Saturday that counter-terrorism officials still hold the view that the plotters were "home-grown," and say there is no evidence of a "mastermind."
However, police said further evaluation was necessary.
The Sunday Times reported the video was being examined frame by frame for any clues as to when and where the video was made.
Anti-terrorist branch investigators have already noted that Khan”s haircut differed noticeabley from its appearance just before the bombings, suggesting that the video was shot months previously.
They will now try to identify clues from his clothing and examine the tape to identify the equipment on which it was recorded.
The Sunday Telegraph said MI5 intelligence officials suspect Khan, a Briton of Pakistani origin, was filmed in Pakistan after receiving orders for the attack.
Senior Whitehall officials told the paper that MI5 is probing the theory that Khan, 30, was filmed during a three-month visit to Pakistan with fellow bomber Shehzad Tanweer, which began in November last year.
A Whitehall official told the Sunday Telegraph that MI5 had no evidence to support reports that the video was produced in Leeds on the eve of the July 7 attacks on three London subway trains and a double-decker bus.
"If this video was made in the UK, in a back room in Leeds, then why are all the bombers not pictured together?" he asked.
However, the Independent newspaper said some experts say the video was probably made in Leeds, because Khan would have been filmed brandishing an automatic weapon if it had been recorded in Pakistan.
Robert Ayers, a security expert at the Royal Institute for International Affairs, told the Independent he thought it was produced in England, but added: "If Khan recorded the video in Pakistan, then that is pretty scary."
Evan Kohlmann, a consultant to the US government on terrorism in Europe, told the Guardian on Saturday that the video bore the hallmarks of an al-Qaeda production.
He said the Khan tape was produced by the al-Sahab video company, which is controlled by al-Qaeda, and the claim of responsibility for the July 7 attacks was done in the same way as its admission of carrying out the September 11 attacks in 2001.
"I find it a little bit depressing that people don”t realize this is al-Qaeda”s calling card. It shows how little some understand about al-Qaeda," he was quoted as saying.