Iain Duncan Smith accused the Government of getting the Treasury to look at the "very worst possibilities" economically if the UK left the EU.
The former Tory leader's warning comes after the Treasury predicted the country would suffer an "immediate and profound" economic shock if it voted in favour of Brexit on June 23.
Duncan Smith told ITV's Good Morning Britain said there were a "number of economists" who didn't agree with the report.
He added that Government supported remaining in the EU and that it had got the Treasury "to look at the very worst possibilities that could happen".
Duncan Smith said that none of the pro-Remain Government reports mentioned the "chaos and crisis that the euro area is bringing".
The former Tory leader argued the EU has become "a friend of the haves rather than a friend of the have nots".Read the full story ›
Iain Duncan Smith has claimed that Home Secretary Theresa May has "refused" to ban the French far-right leader Marine Le Pen from visiting the UK to campaign for the EU referendum Leave campaign.
The former Work and Pensions Secretary voiced concerns that the Front National figurehead would "toxify" the debate if her UK visit went ahead and that she would only be joining the debate in the hope of stirring demands for an in/out referendum in France.
Speaking on ITV's The Agenda tonight he will accuse May of blocking requests to impose a ban.
He will say: "We've asked for her to be banned but the Home Secretary has refused to do it.
"She won't do it. I want her banned, I don't want her over because I think she will toxify the debate. She (Mrs May) can't ban her because of the European Union rules. She said she can't do it."
- Watch The Agenda with Tom Bradby on ITV at 10.35pm tonight.
Iain Duncan Smith broke down and cried during a television interview about the plight of a single mother he had met.Read the full story ›
Around 20 disability campaigners have unfurled banners and shouted slogans in the lobby of the House of Commons over the Government's cuts to benefits.
The protest took place as MPs were in the main Chamber for Prime Minister's Questions.
The demonstrators chanted "No more death from benefit cuts" and brandished a banner asking "Is this how 2 treat disabled people?"
Police officers lined up to prevent any attempt by the protesters to gain access to the Commons chamber but there was no immediate attempt to remove them.
Chancellor George Osborne's Budget has clearer is first parliamentary hurdle, despite a more than £4 billion hole left following his U-turn on disability benefit cuts.
Despite the highly charged debate over the Budget that has developed in recent days, the government won today's main vote on Budget resolutions by 310 votes to 275.
A series of specific budget resolutions, including the cut in capital gains tax, were also passed.
Mr Osborne admitted the now-scrapped disability payment cuts were a "mistake", but stressed that public finances had to be brought under control.
George Osborne has insisted that he will not cut the state pension as he looks to plug a £4 billion 'black hole' in his Budget.
During a debate with MPs, the Chancellor reiterated the Government currently has no plans to make further welfare savings to replace the continued PIP spending.
But he launched a defence of the benefits available to pensioners amid suggestions they need to be reduced to spread the impact of the cuts.
Labour's John McDonnell has said George Osborne is "unfit" for any leading office in government for his "grubby manipulations" in response to his disability benefit U-turn.
Speaking to MPs during the Budget debate, the Shadow Chancellor said the Tory budget process is in "absolute chaos" and urged the Government to rip up its fiscal plan and start again.
"PIPs are the benefits that for many disabled people actually make life worth living."
He added: "The Chancellor was willing to cut away this vital support to some of the poorest and most disadvantaged people of our community. Do not tell us we're all in this together."
The Chancellor has refused to apologise for attempting to introduce "upsetting" cuts to disability benefits before doing a U-turn on the plans.
George Osborne insisted he had listened to and learned from concerns about the cuts to the personal independence payment (PIP) and dropped the proposal.
But he did not accept former shadow chancellor Chris Leslie's invitation to say sorry for the mistake which left a £4.4 billion hole in the Budget.
Mr Osborne has taken the unusual step of opening the final day of debate in person so that he could respond to widespread concerns following ain Duncan Smith's dramatic resignation from the Cabinet.
George Osborne has defended his position as Chancellor as MPs prepare to vote to approve his Budget.
Mr Osborne told the Commons that if Britain wanted to build a "strong and compassionate society" the country had to live within its means.
"We have to back business to create jobs and we have to make sure work pays by putting more money into the pockets of working people."
The Chancellor also used his opening remarks to pay tribute to Ian Duncan Smith, who resigned as Work and Pensions Secretary last week over planned controversial cuts to the welfare budget.