A group calling itself "The Secret Organization of Al Qaeda in Europe" has posted a claim of responsibility for the series of blasts in London, saying they were in retaliation for Britain's involvement in Iraq and Afghanistan.
The statement was published on a Web site popular with Islamic militants, according to Der Spiegel magazine in Berlin, which republished the text on its own Web site.
"Rejoice, Islamic nation. Rejoice, Arab world. The time has come for vengeance against the Zionist crusader government of Britain in response to the massacres Britain committed in Iraq and Afghanistan," said the statement, which was translated by The Associated Press in Cairo.
The authenticity of the message could not be immediately confirmed.
"The heroic mujahedeen carried out a blessed attack in London, and now Britain is burning with fear and terror, from north to south, east to west," the statement said.
"We warned the British government repeated. We have carried out our promise and carried out a military attack in Britain after great efforts by the heroic mujahedeen over a long period to ensure its success."
"We continue to warn the governments of Denmark and Italy and all crusader governments that they will receive the same punishment if they do not withdraw their troops from Iraq and Afghanistan," the statement went on.
It was signed: "The Secret Organization of Al Qaeda in Europe."