Poorer people would suffer the most from Brexit, George Osborne has said.
Today the chancellor will publish a Treasury analysis that will claim Britain's economy would shrink by 6% by 2030 if people vote for Brexit at the June referendum.
Speaking to BBC Radio 4's Today programme, Osborne said the country would be "permanently poorer" outside the EU.
And he labelled those campaigning in favour of Brexit as "economically illiterate".
"We would not all be in this together if we left the EU. The richest in our country would go on being rich, it would be the poorest - the people whose jobs depend on the car plants, whose jobs depend on the steel-making factories and the like - who would be hit if we left the European Union," he said.
"They are the people whose incomes would go down, whose house prices would fall, whose job prospects will weaken. They are the people who always suffer when the country takes an economic wrong term."
In a challenge to the Brexit camp, Osborne said: "Where is your document? Where is your assessment? Where is a single ally or trading partner or credible international organisation that thinks it's a good idea for Britain to leave the EU?"
Eurosceptic Tory MPs immediately hit back. Former cabinet minister John Redwood dismissed Osborne's claim as "absurd".
And Bernard Jenkin said the chancellor "should be ashamed of himself". He told Sky News given Osborne had originally said he would balance the Budget by 2015 "his forecasts are not reliable".
Redwood told Today the Treasury analysis was "completely worthless" as officials had proven themselves to be wrong in the past. "This is a Treasury which had to make huge changes to its forecast for the next two years just between November and March because it decided its November forecast was completely wrong," he said.
And taking aim at David Cameron, Redwood added: "The prime minister was one of the senior advisers working in the Treasury while John Major's government tried to keep this country in the EU's disastrous Exchange Rate Mechanism."
Writing in his Daily Telegraph column today, Boris said the referendum was on a "knife edge" and predicted the UK would have a "glorious future outside the EU".
"All the usual suspects are out there, trying to confuse the British public and to persuade them that they must accept the accelerating loss of democratic self-government as the price of economic prosperity," he said.
"We have heard from the IMF (who got the Asian crisis completely wrong), as well as the banks and the CBI, all of whom were wrong about the euro.
"Davos man – the kind of people whose club class air tickets are paid by the taxpayer, all the lobbyists and corporate affairs directors of the big companies: they are all increasingly nervous that they have been rumbled, that people can see the emperor has no clothes and that Britain could have a glorious future outside the EU.
"They all know that there is one event in the next few weeks that could remind the British people of at least one salient point in this debate – that this country has lost control of its frontiers – and that is another migration crisis on the borders of the EU, and within the EU itself."
This evening cabinet minister Chris Grayling will join Nigel Farage on stage at a pro-Brexit campaign rally.