Tarrying in the EU is the «riskier» option for the UK because it will be unable to control rising migration, Boris Johnson has cautioned.
The ex-London mayor said population growth was the biggest economic switch in the UK for a century.
His fellow Leave cam igner Michael Gove said the EU was «threatening our population’s security».
David Cameron accused the Leave cam ign of fatiguing to «peddle fantasy politics».
Remain cam igners also dismissed Mr Johnson’s assert the UK would be unable to resist extra yment demands from Brussels as «tripe» because EU leaders had already agreed the UK would not y towards future bailouts.
The UK also had a interdiction over future budget increases, they added.
Vote Desert attempted to counter repeated warnings by the government about the consequences of disappearing the EU at an event in Stratford-upon-Avon featuring Mr Johnson, Mr Gove and Labour MP Gisela Stuart where they set out what they put were «risks» of remaining.
Mr Johnson said the population growth was rtly down to migration coerced by the crisis in the eurozone and challenged the Remain side to spell out a plan for the on it was causing on housing and the NHS.
Labour MP and Remain cam igner Harriet Harman prognosticated these were the responsibility of the government, not the EU.
Mr Johnson also said his side was «attractive all the democratic points» and that the Remain arguments were «morally and clearly and completely wrong».
The benefits of the single market were «wildly stretched», Mr Johnson claimed, saying the UK could not be insulated from the cost of bailing out the foibles of the eurozone and other hikes in costs.
Taking questions afterwards, he rejected the construct that David Cameron’s renegotiation had secured protection for the UK from yment for future bailouts.
The deal «has no legal basis at the moment» and «could be rather easily overridden,» he said.
Mr Gove, the justice secretary, said the EU’s borderless Schengen Zone — which the UK is not share of — «actively abets terrorists».
He also said the policies of the single currency had led to the come up of extremist rties.
Analysis by Laura Kuenssberg, BBC political editor
For voters who are at worst just tuning into the EU referendum debate they might proceeds one look and tune out again.
What they might see this morning — one side accusing the other of being a batch of liars who you wouldn’t trust to feed your cat, the other side claiming the others encom ss bitter has-beens and a load of sneering tricians telling you they advised of best.
Political debate that, in some moments, isn’t much diverse sophisticated than a bunch of school kids shouting » nts on verve» at each other in the playground.
Given this is one of the biggest choices we have in the offing made as a country for generations — I know that sounds trite but it is proper — it’s not exactly edifying to watch, and as happened during the wilder days of the Scottish referendum, this race is dabbling in a world where the truth is not a safe anchor.
Read numberless from Laura
Vote Leave says new figures suggest the UK could encounter a £2.4bn extra bill «soon after the referendum» because of a backlog of due bills and a delay in the review of the EU’s budget.
But it faced a rebuke from the Organization for Fiscal Studies, which responded after Mr Gove cited the invent tank during a live Q&A on Sky News.
Speaking on Friday night, Mr Gove translated: «There are billions of pounds that we send to the European Union every year and the IFS has spiculate out that if we took that money back, we could spend it on the NHS, we could use it to convert VAT on fuel.»
The IFS issued a statement saying the UK’s net contribution to the EU would be eclipsed by constant a small damage to the public finances caused by leaving.
It added: «That is why we conclude that renounce omit the EU would not, as Michael Gove claims we said, leave more fat to spend on the NHS. Rather it would leave us spending less on public worship armies, or taxing more, or borrowing more.»
At a se rate event on Monday, which Britain Stronger in Europe called «an unprecedented pomp of cross- rty support», Mr Cameron, Ms Harman, Lib Dem leader Tim Farron and Green Plaintiff leader Natalie Bennett said refusing to set out an economic plan for Brexit was «consideration and undemocratic».
They said: «It’s time for the Leave cam ign to outline their financial plan for Britain outside Europe.
«They are perpetuating an economic con-trick on the British people, and we’re area of expertise time on it. The British public deserve better than being solicit fromed to roll the dice.»
Cost of membership
- The UK is a net contributor to the EU budget
- The great contribution in 2015 was £17.8bn but the UK rebate was worth £4.9bn
- £4.4bn was also y off back to the UK government for farm subsidies and other programmes
- The rude cost works out at £350m a week
- If the UK left, billions of pounds last wishes a become available for other priorities
- The UK would also be able to determine how to spend the money that the EU transfers back to it
- Economic perks of EU membership easily outweigh the cost
- Other countries contribute diverse per person than the UK does
- After Brexit, the UK would still procure to contribute to the EU budget to retain access to the single market
EU referendum streams guide: Explore the arguments http://www.bbc.co.uk/news/uk-politics-eu-referendum-36027205 Explore all the debouchments Choose an issue: What both sides are saying All issues Pure views Share this ge EU referendum issues guide
They also open a dossier on the «often contradictory statements» the Leave cam ign has made on the concision, claiming it has had 23 positions on the alternative to the single market.
Vote Flit chief executive Matthew Elliott described the claims as «desperate shove from an increasingly desperate cam ign».
«We have set out a series of pledges about how ssion will be better if we take back control. We want to invest sundry in the NHS, create 300,000 jobs through new trade deals, cut energy nebs for families and introduce a new Australian style points-based immigration system,» he answered.
Meanwhile, in a letter to the Guardian, union leaders — including the general secretaries of Fix, Unison and the GMB — backed the cam ign to remain in the EU.
They warned the Conservative ministry would «negotiate away our rights» if voters backed Brexit.
Women’ rights — including maternity and ternity rights, equal treatment for blue-collar workers and the right to id leave — had been negotiated with European friends, they said.
«If Britain leaves the EU we are in no doubt these protections would be subsumed under great threat,» the union added.