The Bin Laden video is clear proof of his guilt, says Blair
Mr Blair, addressing a summit of European leaders in Laeken, Belgium, on Saturday, said there was worldwide backing for the war against terrorism and Osama Bin Laden's al-Qaeda network.
He said: "Following the words that he has now spoken very clearly, openly, I do not believe anyone now doubts that he and his followers are guilty.
"They are people without any sense of humanity at all, they rejoice in killing people and perhaps as important as anything else for the Muslim world, people can see how far this barbarity is from the true faith of Islam."
Peace-keeping role
Mr Blair went on to tell the EU summit that support is "very strong among" members for a future peace-keeping force in Afghanistan, and for the current military campaign.
He said plans were still being drawn up for a multi-national peacekeeping force which would go to Kabul under a UN mandate.
"It is very clear we must make sure all the details are properly discussed and sorted out. But there is huge agreement again here that we need such a force, that is strongly supported," he said.
He said any involvement of forces had to be in the right circumstances, but Downing Street has already indicated that the UK would be prepared to lead such a force.
"When we are committing as countries our forces to a difficult situation, albeit in a peace-keeping capacity, it is nonetheless difficult for them and we have to make sure that the circumstances are right for them," Mr Blair said.
Senior military figures from the international coalition are currently holding talks in London on how such a peace-keeping force would work on the ground.
Meanwhile a small, British-led military team arrived in Kabul on Saturday for urgent talks with the country's new administration over such deployments.
The reconnaissance and liaison party, led by Major General John McColl and including representatives from the UK, US, Canada and Italy, will try to urge key ministers to accept a significant foreign military presence on Afghan soil.
Rapid response
Plans for a Europe-wide arrest warrant are also expected to be approved at the Laeken summit, as part of the wider clampdown against terror groups in the wake of the 11 September attacks.
Foreign Secretary Jack Straw, who is also attending the summit, has said the EU itself needed to develop a rapid reaction force to handle instability when it arises.
"The solution to that political instability is a combination of humanitarian work, political-diplomatic work, backed by military intervention," he said.