Tony Blair has insisted Brexit is not “inevitable”, as he urged “millions” of Britons worried about leaving to fight to stop it.

In a controversial intervention in the Brexit debate, the former Prime Minister called for a “revolt” to halt withdrawal, similar to the populist wave that won the referendum.

“The one incontrovertible characteristic of politics today is its propensity for revolt,” Mr Blair told a London audience.

“The Brexiteers were the beneficiaries of this wave, but now they want to freeze it to a date in June 2016.

“They will say the will of the people can’t alter. It can. They will say that leaving is inevitable. It isn’t.

“They will say they don’t represent the will of the people. We do, many millions of them and – with determination – many millions more.”

Mr Blair added: “This is not the time for retreat, indifference, or despair, but the time to rise up in defence of what we believe – calmly, patiently, winning the argument by the force of argument, but without fear and with the conviction we act in the true interests of Britain.”

The former Labour leader also sought to point out the huge costs to the country of a Government focused – inevitably – on the enormous challenge of negotiating a successful withdrawal.

He said: “This is a Government for Brexit, of Brexit and dominated by Brexit. It is a mono-purpose political entity.

“Nothing else truly matters: not the NHS, now in its most severe crisis since its creation; not the real challenge of the modern economy, the new technological revolutions of AI and Big Data; not the upgrade of our education system to prepare people for this new world; not investment in communities left behind by globalisation; not the rising burden of serious crime; or bulging prison populations; or social care; not even, irony of ironies, a genuine policy to control immigration.”

Mr Blair poured scorn the claims that EU membership – and, in particular, rulings by the European Court of Justice (ECJ) – prevent Britain being a truly independent country.

“On the ECJ, I would defy anyone to be able to recall any decisions which they might have heard of, as opposed to the decisions of the European Court of Human Rights, a non-EU body,” he said.

“I can honestly say that during all my time as PM there was no major domestic law that I wanted to pass which Europe told me I couldn't.”

Before the speech, Iain Duncan Smith, the former Conservative Cabinet minister and a prominent Leave campaigner, condemned the speech as arrogant and utterly undemocratic.

But Mr Blair said: “The people voted without knowledge of the true terms of Brexit.

“As these terms become clear, it is their right to change their mind. Our mission is to persuade them to do so.

“What was unfortunately only dim in our sight before the referendum is now in plain sight. The road we're going down is not simply Hard Brexit. It is Brexit At Any Cost.

“Our challenge is to expose relentlessly what this cost is, to show how the decision was based on imperfect knowledge which will now become informed knowledge, to calculate in ‘easy to understand’ ways how proceeding will cause real damage to our country; and to build support for finding a way out from the present rush over the cliff’s edge.