200 men from 40 Commando are being deployed
His remarks came as the Ministry of Defence (MoD) announced that 200 Royal Marine commandos were on standby for expected US-led land operations against the Taleban regime.
Mr Blair said the move was a "huge responsibility", but it had to be done to defend "civilised values" around the world.
And if Bin Laden and his al-Qaeda terrorist network were not stopped, he warned, there was a danger they could acquire "chemical, biological, even nuclear weapons of mass destruction".
"If they are allowed to carry on doing this, our world will be an insecure, unsafe place and there will be no corner of the world - particularly not a place like Britain - that will be untouched by that," Mr Blair said.
Standby commandos
Armed Forces Minister Adam Ingram said on Friday that 200 troops from 40 Commando would remain in the region for possible use on the ground, when colleagues return home from a training exercise in Oman.
Both the Conservatives and Liberal Democrats voiced their support for the move, which Mr Ingram said was a "major enhancement" in the capacity of coalition forces.
The troops on standby will form part of a "large and flexible" force, totalling 4,200 personnel, and supported by a substantial amount of hardware.
Aircraft carrier HMS Illustrious, a submarine armed with cruise missiles, the destroyer HMS Southampton and the frigate HMS Cornwall will remain in the region.
The minister said seven Royal Fleet Auxiliary ships and four support aircraft - Nimrod maritime patrol and Hercules transport planes - will stay behind too.
Another 400 troops from 40 Commando would be on standby in Britain when they return to their base in Taunton, Somerset from Oman next week.
Chief of Defence Staff Admiral Sir Michael Boyce said the marines could be used to mount "precise surgical raids" against targets such as Taleban control-and-command centres or ammunition dumps.
He said if the US-led operation expanded further, Britain did have "much, much larger forces we could bring to bear".
Nuclear weapon fears
British officials believe that Bin Laden does not yet have the capacity to mount a nuclear attack, but Mr Blair's comments suggested the depth of the concern in London and Washington.
However there have been reports that intelligence sources indicated that Bin Laden had already illegally acquired nuclear materials from Pakistan, which has a nuclear capability.
Mr Ingram said the force was "primarily configured to assist in the coalition's air campaign".
He refused to say whether the troops were planned to be used in any ground operations.
But defence analysts said the smaller force suggested the strategy would include short, sharp ground raids.
40 Commando is part of the Royal Marines' 3,500-strong 3 Commando Brigade, all of whom are trained for winter warfare and Arctic fighting.
Ramadan concerns
Britain is so far the only country other than the US to have taken part in the military action - mainly in a supportive logistics role.
Shadow defence secretary Bernard Jenkin reaffirmed Conservative support for the military campaign.
"To fail would be a fatal signal and encouragement to the terrorists and to those who sustain them, not just in Afghanistan but around the world," he said.
But one of the chief British critics of the coalition's bombing campaign, senior Labour MP Tam Dalyell said it would be "absolute folly" in terms of the Islamic and Arab world to conduct military operations during Ramadan in November.