A previously-unseen video of one of the 7/7 suicide bombers has been shown on al-Jazeera television today to coincide with tomorrow’s first anniversary of the atrocity.

Shehzad Tanweer, 22, a university dropout from Beeston, Leeds, is shown speaking with a Yorkshire accent, wearing a Muslim headscarf and jabbing his finger at the camera.

In an apparent message to the British Government, he vows that attacks will continue until troops are pulled out of Iraq and Afghanistan and "you stop your support" for America and Israel.

He says: "What have you witnessed now is only the beginning of a string of attacks that will continue and become stronger until you pull your forces out of Afghanistan and Iraq and until you stop your financial and military support to America and Israel."

Tanweer trained in terrorist camps in Pakistan. He detonated his device on an eastbound Circle Line Tube train in Aldgate, East London, killing six people.

In total, 52 innocent people died in the bombings on July 7 last year, which were carried out by Tanweer, Mohammad Sidique Khan, 30, Hasib Hussain, 18 and Jermaine Lindsay, 19, on three underground trains and a double decker bus.

In the video Tanweer refers to the non-Muslims of Britain. According to a BBC translation, he said that because they voted for a government which "continues to oppress our mothers, children, brothers and sisters in Palestine, Afghanistan, Iraq and Chechnya", then they deserve such actions.

The video also features a statement from Ayman al-Zawahri, al-Qaeda’s second in command, suggesting a strong link between the bombers and Osama bin Laden’s terror network.

The video is likely to cause further distress to the scores of bereaved families and survivors who were preparing to honour the victims of the blasts although Jacqui Putnam, a 55-year-old analyst programmer who was on the Tube at Edgware, said today: "Nothing’s going to overshadow this anniversary. Tomorrow we’re just going to mourn the dead and show they’re not going to intimidate us."

The footage seems to have been taken in the same place as footage of Muhammed Sidique Khan that was shown in September 2005. Both men wear the same red and white chequered headscarf and the background and the carpet is the same in the videos.

Intelligence chiefs and police have always insisted that the four men acted alone and had no link to any terror organisation. But the tape of Tanweer could provoke new demands for a full public inquiry.

Security sources have previously dismissed Khan’s video, which was also cut with comments from Zawahiri, as "propaganda" and insisted it did not prove that the terror network had any direct hand in the London atrocity.

Experts have always wondered why final video tape messages from the other three bombers had never been released, as is the custom.

The only other video testament from any of the four bombers to emerge before today had been from Khan, the gang’s ringleader. Tanweer is considered by investigators to have been his right-hand man.

Andy Hayman, MPS Assistant Commissioner, Specialist Operations, said today after the video was released: "We are aware of the tape and this will form part of our investigation.

"There can be no doubt that the release of the video at this time can only cause maximum hurt and distress to the families and friends of those who died on 7/7 and the hundreds of people who were injured in the terrorist attacks.

"We are sure that the overwhelming majority of all communities are united in condemning any attempt to justify last year's terrorist attacks in London.

"We would like to reassure the public that police are doing all they can to ensure their safety. It is important that people continue to go about their daily lives as normal, to do otherwise would mean the terrorist has won."

At Tanweer's family home in the inner-city Leeds suburb of Beeston, a young man stood guard at the gate to deter visitors.

He said that the family had no comment to make on the sucide video. "What part of go away do you not understand?" he asked.

Later, the back door of the semi-detached property stood open and the sound of voices could be heard inside the house, which had a typed notice taped to the kitchen window: "To the attention of the media. We have no comment to make. Please do not knock on the door."

An older woman, thought to be the suicide bomber's mother, Parveen Tanweer, came to the door and declined to answer questions about the video message.

"Excuse me. You know where the gate is. Just go," she said.

Speculation about the existence of a video testament from Tanweer stretched as far back to last September, when Khan’s video was first broadcast.

Detectives believe that Khan’s video could well have been filmed abroad, possibly during his trips to Pakistan, and reports last year suggested that Tanweer could have filmed a message at around the same time.

Tanweer’s video is likely to be subject to intensive visual scrutiny and painstaking forensic analysis in the hope it could yield vital clues.

Khan’s video was shown for the first time on September 1 by al-Jazeera, which is based in Qatar. In that video, Khan claimed that the British public were to blame for the terror attacks, saying that it was their support for the Western governments which "continuously perpetuate atrocities" against the Islamic world that made them "directly responsible".

"We are at war and I am a soldier," the 30-year-old, who was from Dewsbury, West Yorkshire, declared to widespread condemnation.

Khan’s video bore the "al Sahab" logo, which means "The Clouds" and is a signature of al-Qaeda recordings. It is still regarded by investigators as the best evidence of the group’s motivation for the attacks.

The Tanweer video could yet provide detectives with key clues in the hunt for those who supported the London bombers. Earlier this week, detectives said they were still seeking those who helped prepare the bombers for their lethal mission.

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