Tony Blair has launched a powerful attack on 'absurd' British Islamists who have nurtured a false 'sense of grievance' that they are being oppressed by Britain and the United States.

In his most outspoken remarks on Islamists, the former Prime Minister warns that Britain is in danger of losing the battle against terrorists unless mainstream society confronts the threat.

Blair's remarks, in which he also attacks some civil liberty campaigners as 'loopy loo', were made in a Channel 4 documentary recorded last Tuesday on the eve of his departure from Downing Street.

'The idea that as a Muslim in this country that you don't have the freedom to express your religion or your views, I mean you've got far more freedom in this country than you do in most Muslim countries,' Blair told Observer columnist Will Hutton, who presents the documentary.

'The reason we are finding it hard to win this battle is that we're not actually fighting it properly. We're not actually standing up to these people and saying, "It's not just your methods that are wrong, your ideas are absurd. Nobody is oppressing you. Your sense of grievance isn't justified."'

Blair held out the example of the overthrow of the Taliban in Afghanistan - criticised by Islamists as an example of the heavy-handed imperial West oppressing Muslims - to highlight unfounded claims of grievance. He asked how it is possible to claim that Afghanistan's Muslims are being oppressed when the Taliban 'used to execute teachers for teaching girls in schools'.

Blair added: 'How are [we] oppressing them? You're oppressing them when you support the people who are trying to blow them up.'

Blair, who normally chooses his language carefully when he talks about Islamists, also takes a swipe at critics who accused him of undermining civil liberties. 'When I'm trying to change the law in order to make it easier to deport people who engage in terrorism - the idea that that's an assault on hundreds of years of British civil liberties is completely absurd. Some of what is written on this is loopy-loo in its extremism.'

· The Last Days of Tony Blair will be shown on Channel Four at 8pm tomorrow