Brexit could cause the European Union to break down by triggering efforts by other nations to secede, the Swedish foreign minister has said.

An exclusive poll for The Independent found that the campaign for Britain to leave the EU has opened up a 10-point lead against Remain in a reversal of the position one year ago.

Margot Wallstrom, the foreign minister of Sweden, said other nations could follow the UK with referendums and demands from reform if it votes Out on 23 June.

“The spill-over effect will be deeply felt,” she said on the BBC's This Week's World programme.

"That might affect other EU member states that will say: ‘Well, if they can leave, maybe we should also have referendums and maybe we should also leave.’

"If they stay, it might also lead to other countries saying: 'Well, they negotiated, they asked and demanded to have a special treatment so why shouldn't we?'"

Ms Wallstrom is one of many European leaders hoping the UK will remain in the alliance, saying it was an important trading partner and home to around 90,000 Swedes.

The most scaremongering arguments for Brexit Show all 7 1 /7 The most scaremongering arguments for Brexit The most scaremongering arguments for Brexit 22 May 2015 In his regular column in The Express Nigel Farage utilised the concerns over Putin and the EU to deliver a tongue in cheek conclusion. “With friends like these, who needs enemies?” PA The most scaremongering arguments for Brexit 13 November 2015 UKIP MEP for Yorkshire and North Lincolnshire Mike Hookem, was one of several political figures who took no time to harness the toxic atmosphere just moments after Paris attacks to push an agenda. “Cameron says we’re safer in the EU. Well I’m in the centre of the EU and it doesn’t feel very safe.” Getty Images The most scaremongering arguments for Brexit 19 April 2016 In an article written for The Guardian, Michael Gove attempts to bolster his argument with a highly charged metaphor in which he likens UK remaining in the EU to a hostage situation. “We’re voting to be hostages locked in the back of the car and driven headlong towards deeper EU integration.” Rex The most scaremongering arguments for Brexit 26 April 2016 In a move that is hard to decipher, let alone understand, Mike Hookem stuck it to Obama re-tweeting a UKIP advertisement that utilises a quote from the film: ‘Love Actually’ to dishonour the US stance on the EU. “A friend who bullies us is no longer a friend” The most scaremongering arguments for Brexit 10 May 2016 During a speech in London former work and pensions secretary Ian Duncan Smith said that EU migration would cause an increasing divide between people who benefit from immigration and people who couldn’t not find work because of uncontrolled migration. “The European Union is a ‘force for social injustice’ which backs the ‘haves rather than the have-nots.” EPA The most scaremongering arguments for Brexit 15 May 2016 Cartoon character Boris Johnson made the news again over controversial comments that the EU had the same goal as Hitler in trying to create a political super state. “Napoleon, Hitler, various people tried this out, and it ends tragically.” “The EU is an attempt to do this by different methods.” PA The most scaremongering arguments for Brexit 16 May 2016 During a tour of the women’s clothing manufacturer David Nieper, Boris had ample time to cook up a new metaphor, arguably eclipsing Gove’s in which he compares the EU to ‘badly designed undergarments.’ “So I just say to all those who prophecy doom and gloom for the British Business, I say their pants are on fire. Let’s say knickers to the pessimists, knickers to all those who talk Britain down.” Getty Images

Several politicians have raised concerns that Brexit could spark the dismantling of the entire EU, as well as domestic fears that it could threaten the UK’s existence by provoking another independence referendum in Scotland.

Former Prime Ministers Sir John Major and Tony Blair called the prospect a “historic mistake” last week.

US President Barack Obama has been vocal in his support of David Cameron’s position in the Remain camp, while presumptive Republican presidential candidate Donald Trump has backed a Brexit.

The survey of 2,000 people for The Independent by ORB found that 55 per cent believe the UK should leave the EU (up four points since our last poll in April), while 45 per cent want it to remain (down four points).