Staying in the EU will see steep levels of immigration, Justice Secretary Michael Gove is warning, as he accused the Remain side of treating voters like children.
In a hard-hitting speech, the Cabinet heavyweight insisted remaining in the EU was the danger option as the ability of Britain's intelligence services to keep the country safe would be "undermined" by the European Court of Justice unless Brexit won.
The prominent Leave campaigner insists the Government has admitted in a Treasury document warning of the economic costs of withdrawal that immigration will soar if Britain stays in the EU.
"The report from the Treasury is an official admission from the In campaign that if we vote to stay in the EU then immigration will continue to increase by hundreds of thousands year on year," he said.
"Over 250,000 people came to Britain from Europe last year. As long as we are in the EU we cannot control our borders and cannot develop an immigration policy which is both truly humane and in our long-term economic interests."
Mr Gove says the European Court of Justice (ECJ) is poised to damage Britain's "Five Eyes" intelligence-sharing pact with the US, Canada, Australia and New Zealand, through the Charter of Fundamental Rights.
"The ECJ has recently used the charter to make clear that it can determine how our intelligence services monitor suspected terrorists.
"How long before the ECJ starts undermining the Five Eyes intelligence-sharing agreements that have been a foundation of British security since 1945, and which are the source of jealousy and suspicion in Brussels?"
The intervention came as a new poll for the Daily Telegraph showed the Remain side leading by 52% to 43%, as Chancellor George Osborne defended Treasury claims that Brexit could see every household in the country £4,300 a year worse off than if the UK remained in the EU.
Treasury analysis predicted that withdrawal would mean public services could suffer to the tune of £36 billion a year.
Leave campaigners dismissed the 200-page government analysis as a "dodgy" document, and the methodology used was widely mocked on social media.
The Chancellor tried to make light of criticism of the equation used by the Treasury to calculate the figures by joking: "That's a gravity model - a regression gravity model with a general equilibrium NiGEM model for the economy. Obvs."
Speaking on ITV's The Agenda, Mr Osborne said: "One of the things we've proved, if you don't have as much money coming into the country, either you have a big hole in your public finances, or you put income tax up by eight pence.
"Let's be clear, Britain would be poorer. Don't pretend that the economy won't suffer."
The Chancellor also faced questions over the assumption used in the document that net migration would be 185,000 a year from 2021 onwards - far in excess of the Government's goal of reducing it to the "tens of thousands" - with Leave supporters arguing that the Treasury had failed to take into account the costs of coping with an ever-growing population.
Seizing on the figures, Mr Gove warns that the ECJ's role in interpreting the Charter of Fundamental Rights would be bad for Britain's border controls.
"The European Court can now control how all member states apply the crucial 1951 UN convention on asylum and refugees because the charter incorporates it in EU law. So Britain has lost control of a vital area of power and the European Court will increasingly decide how our policy must work."
The Justice Secretary accuses the In campaign, backed by Prime Minister David Cameron, of patronising voters.
"The Remain campaign want us to believe that Britain is beaten and broken. It treats people like mere children, capable of being frightened into obedience by conjuring up new bogeymen every night.
"If we vote to remain ... we'll be told by Brussels to 'shut up and suck it up'."
He says the European Court would also have the final say on proposals to allow prisoners to vote.
The Justice Secretary was criticised by business minister Anna Soubry who warned that he was unable to explain what leaving the EU would mean for people.
The Treasury analysis examined three potential options for the UK if it left the EU - the status currently enjoyed by Norway, which makes payments to the EU and accepts free movement in return for access to the single market, a bilateral free trade deal of the kind obtained by Canada, or a relationship under the rules of the World Trade Organisation.
Under the terms of a Canadian-style bilateral trade deal with Brussels, the economy would be 6.2% smaller by 2030, the equivalent of £4,300 per household, the analysis suggested.
The Treasury document suggests that the Norway-style approach would see GDP fall by a central estimate of 3.8% in 2015 terms, the equivalent of £2,600 per household.
If there was no deal with the EU, and the UK fell back on WTO rules, the economy would suffer by between 5.4% and 9.5%, with a central estimate of a 7.5% fall - hitting each household by £5,200.
The analysis suggests that Norwegian-style European Economic Area membership would result in £20 billion lower public sector net receipts, the Canadian approach would leave the public sector £36 billion worse off and the WTO route could mean £45 billion less for services.
Pro-Brexit minister Andrea Leadsom, who had served in the Treasury under Mr Osborne, mocked the report's long-term prediction, telling BBC Radio 4's World at One: "It's extraordinary to have such an accurate central figure and it implies a clarity of crystal-ball gazing that even I, as a fully paid up witch, couldn't possibly presume."
Labour leader and Remain backer Jeremy Corbyn said he wanted more details on how Mr Osborne made the calculation.