Staying in the EU will make the UK more vulnerable to Paris-style terrorist attacks, Work and Pensions Secretary Iain Duncan Smith has told the BBC.
Mr Duncan Smith, who is campaigning for an EU exit, also questioned the effectiveness of curbs to migrants’ benefits on immigration to the UK.
The senior minister’s comments directly contradict David Cameron, who says the UK is “safer and stronger” in the EU.
He says the UK’s future is in a “reformed” European Union.
The PM has also warned that leaving the EU would give the UK an “illusion of sovereignty” but not full control.
Earlier, UKIP leader Nigel Farage had said a vote to leave would mean the UK was “in charge of our own country”.
BBC assistant political editor Norman Smith said London mayor Mr Johnson had been genuinely conflicted but had now made up his mind – and was expected to announce he was joining the leave campaign.
Mr Cameron’s latest comments came as ministers began campaigning to win over voters ahead of a referendum on 23 June over the UK’s EU membership.
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On the BBC’s Andrew Marr Show, Mr Cameron defended his renegotiation of Britain’s terms of EU membership, reached after two days of intense wrangling with EU leaders in Brussels this week.
He said he had secured reforms “people said weren’t achievable”, including curbs to migrants’ benefits and exempting Britain from “ever closer union”.
The offer on the table was a “better” deal for the UK and would be “legally binding”, he said.
‘Safety in numbers’
Making his case for why Britain should stay in a “reformed” EU, Mr Cameron said it would safeguard the UK position in the single market and help in the fight against terrorism and crime.
“Safety in numbers in a dangerous world,” he said.
Proponents of Britain leaving the EU have argued it would give Britain back control of itself.
But Mr Cameron warned: “If we leave the EU that might give you a feeling of sovereignty – but is it real?
“Would you have power to help businesses not be discriminated against in Europe? No, you wouldn’t. Would you have the power to insist European countries share with us their border information so we know what terrorists and criminals are doing in Europe? No, you wouldn’t.
“So you have an illusion of sovereignty but you don’t have power, don’t have control, you can’t get things done.”
Mr Cameron also appealed to Mr Johnson not to join six ministers who attend cabinet in campaigning to leave the EU.
“I’d say to Boris as I say to everyone else – we will be safer, stronger, better off inside the EU.
“I think the prospect of linking arms with Nigel Farage and George Galloway and taking a leap into the dark is the wrong step for our country.
“And if Boris and others really care about getting things done in our world, the EU is one of the ways in which we get things done,” he said.
BBC political editor Laura Kuenssberg says Downing Street has been resigned to Mr Johnson campaigning to leave following a meeting this week which left him disappointed with Mr Cameron’s plans on the EU.
Also on the Marr Show, UKIP leader Nigel Farage criticised the scope of the PM’s reform deal, saying it could be vetoed by the European Parliament and the European Court of Justice.
“There is one absolute certainty if we vote to leave… and that is that we will be in charge of our own country, we will make our own laws, we will run our own ministerial departments,” he said.
He said the UK had ceded too much “control of our own future” to the institutions in Brussels.
A similar argument was put forward by employment minister Priti Patel, who is campaigning for an EU exit. She told the BBC’s Pienaar’s Politics that the referendum was a chance for the UK to “take back control”.
By remaining a member of the EU, key decisions made in the UK risked “being ridden over roughshod” by the European Court and EU institutions, she argued.
On Marr, Scottish First Minister Nicola Sturgeon warned that if the UK voted to leave the EU but Scotland did not, it would “almost certainly” trigger demands for another referendum on Scottish independence.
The prime minister announced the date of the in/out referendum outside Number 10 on Saturday, having returned from Brussels with a deal he argued gave Britain a “special status” within the EU.
The EU agreement on the renegotiations of the UK’s relationship with Europe would take effect immediately if the UK voted to remain in the EU on 23 June.
It includes changes to allow curbs on migrant welfare payments, safeguards for Britain’s financial services and making it easier to block unwanted EU regulations.
‘Mired in the past’
Splits in the cabinet over the issue have been laid bare by interviews and articles in Sunday’s newspapers.
Writing in the Observer, Foreign Secretary Phillip Hammond said “leaving the EU would be a threat to our economic security and our national security”.
In an article for the Mail on Sunday, Business Secretary Sajid Javid said he would be voting for the UK to remain in the EU with a “heavy heart” and no “enthusiasm”. He said leaving the EU could add to “economic turbulence”.
However, Justice Secretary Michael Gove – a close friend and key ally of Mr Cameron – wrote in the Sunday Telegraph that the EU was “mired in the past”. He said choosing to join the leave campaign had been “the most difficult decision of my political life”.
Northern Ireland Secretary Theresa Villiers told the BBC leaving the EU was a safer option than staying in it.
She said there had been a sense of history at the cabinet meeting to discuss the vote – the first to be called on a Saturday since the Falklands War.
The Labour Party, the SNP, Plaid Cymru and the Lib Dems have said they are in favour of staying in Europe. The DUP said it will recommend voting to leave the EU.
Two campaign groups – Vote Leave and Leave.EU – are competing to be officially designated as the Out campaign for the referendum.
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The key points of Mr Cameron’s deal, agreed in Brussels on Friday, are:
- an “emergency brake” on migrants’ in-work benefits, with payments phased in during their first four years in a new country, when there are “exceptional” levels of migration. The UK will be able to operate the brake for seven years
- child benefit for the children of EU migrants living overseas will now be paid at a rate based on the cost of living in their home country – applicable immediately for new arrivals and from 2020 for the 34,000 existing claimants
- The amending of EU treaties to state explicitly that references to the requirement to seek ever-closer union “do not apply to the United Kingdom”, meaning Britain “can never be forced into political integration”
- The ability for the UK to enact “an emergency safeguard” to protect the City of London, to stop UK firms being forced to relocate into Europe and to ensure British businesses do not face “discrimination” for being outside the eurozone
Critics say his deal does nothing to tackle high levels of immigration or take back powers from Brussels.
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