A man claiming to be one of the four bombers behind the London July 7 attacks made an appearance on an Arab TV and threatened to strike again.
The man, identified as Mohammad Sidique Khan, 30, talked about his motives in a tape-recorded footage released on al-Jazeera. He spoke in English with a Yorkshire accent.
Khan said the UK government had committed atrocities against Muslims and he was inspired by Osama Bin Laden.
In a second video, al-Qaeda's Ayman al-Zawahiri claimed responsibility for the blasts and threatened new attacks.
It is not clear when or where either tape was filmed, BBC said in a news released Thursday night.
The eldest of the four bombers, Khan was responsible for the Edgware Road Circle Line explosion which killed six people and injured 120.
On the tape, the man says bombings in London and in Madrid were the fault of "Western citizens" and the public should no longer feel safe as they would be targeted again.
With a West Yorkshire accent, he said: "Our words are dead until we give them life with our blood. I and thousands like me have forsaken everything for what we believe."
He said the public was responsible for the atrocities perpetuated against his "people" across the world because they supported democratically elected governments who carried them out.
"We are at war and I am a soldier. Now you too will taste the reality of this situation."
In a separate recording, al-Zawahri said the London underground attacks were a "slap" to the policies of Prime Minister Tony Blair.
Speaking in Arabic, he said the bombings were proof that al- Qaeda had moved the battle to "the enemy's land."
Scotland Yard has confirmed it is aware of the tape.
The British Foreign Office has said it will not comment on any aspects of the video.