GETTY A Brexit could mean millions of British job losses

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The referendum on the European Union has escalated as 'In' campaigners warn that Britain will be punished if it votes for independence from Brussels. Campaigners believe that the EU would make British taxpayers pay for their decision.

Eurosceptics have attacked the latest campaign threat as scaremongering and blackmail. Those in the 'Out' campaign argue that trade would not be affected by an exit, often citing Norway, which is not a member but still a large exporter to the EU. Lord Lawson, the new head of a Conservative Brexit campaign, said Britain could “negotiate a free trade deal with the rest of Europe”, entailing “a more amicable and realistic relationship”. But ‘In’ campaigners claim that a vote to withdraw from the EU would threaten millions of British jobs. Under EU rules, the 27 countries would negotiate between themselves to determine the terms of any new relationship, meaning that Britain wouldn't get a say in any new deal.

GETTY David Cameron arrives at the Tory Party Conference

The procedures for EU exit are outlined in Article 50 of the Lisbon Treaty, which states: “The member of the European Council or of the Council representing the withdrawing member state shall not participate in the discussions of the European Council or Council or in decisions concerning it.” Lucy Thomas, deputy director of The IN Campaign and campaign director at Business for New Europe, added that Britain could end up more powerless outside the EU. Ms Thomas said: “This means Britain would just get a deal handed to us by the remaining EU states in the end. We could suggest what terms we would like, but we wouldn’t get a casting vote. “Those who want to take us out of the EU can say we’ll have a relationship like that of Norway or Switzerland, but the fact is that we don’t get to choose our deal. We would be outside the negotiating room the second you vote to leave.”

GETTY George Osborne could be faced with a tough new trade deal after a Brexit

Lib Dem leader Tim Farron added: “This information is damning for the ‘Out’ campaign and shows that being in Europe, fighting for reform and change is far better than carping from the sidelines. "What it also means is having the rules being dictated to us to try to regain access to the common market. Our economy and millions of jobs are based on trade and business with Europe.” A former senior Eurocrat said: “Article 50 foresees a procedure whereby, once a member state declares its intention to leave, it is excluded from the decision-making apparatus of the Union and negotiations about the future relationship between the Union and the state in question are immediately opened. "Put another way, the UK would have to negotiate such a new relationship from the outside and would find itself in a weak position, relative to the other 27 united member states.”

But Owen Paterson, one of the Conservatives’ most prominent Eurosceptics, argued that the UK’s economic prowess would ensure that the UK retained a favourable relationship with the EU. He said that unlike much of the EU, Britain is growing as a stable economic power. He said: "This is rubbish. We’re the fifth largest economy in the world. "Five million EU jobs are dependent on exports to the UK, one million German jobs rely on the UK.

GETTY Britain would not get a casting vote in a new EU trade deal

“This whole argument is completely laughable. Are they really saying we would be treated like a Sudan or a North Korea? We will do a deal with the EU. We would be massively empowered.” The news comes as the EU question looks to dominate this week's Conservative Party conference. This morning on the Andrew Marr Show, David Cameron said he couldn't rule out campaigning for a Brexit. He said that he wanted to win concessions, such as controlling benefit payments, before endorsing any side of the vote. Mr Cameron admitted: "If I don't get what I want I am ruling nothing out."