The Association of British industry has warned Conservative top candidates against a brexit without a deal.
Such a scenario would cause “serious” damage to businesses, said the panel-which supports the party-to all MPs.
General director Carolyn Fairbairn told BBC Radio 4’s Today program that a no-deal Brexit should be an option “not even considered”.
She said after the CBI had sent an open letter to candidates.
In her letter, the CBI says: “companies big and small are clear that leaving the EU with a deal is the best way forward.”
“Short-term disturbances and long-term damage to UK competitiveness will be serious if we get along without one. The vast majority of companies can never be prepared for a no-deal, especially our [small and medium-sized] members who cannot afford complex and costly contingency plans.”
She said Today that companies were not ready for a no-deal scenario, and said: “this idea that we are ready, is simply not true”.
“How can they be prepared for 20 billion pounds higher customs costs? How can you prepare for fare increases overnight? 150,000 companies without corresponding systems are in operation.
“This is not a responsible strategy for a government.”
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The United Kingdom is expected to enter into force on 29 June 2014. The EU will join the EU on 30 June 2014. Theresa May, however, applied for an extension and the deadline was extended until 31 December 2012. It was extended by 31 March. October moved.
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Esther McVey, the first of the 12 confirmed contenders in the Tory leadership race, said earlier this week in a column for the Daily Telegraph that Britain must “actively accept an exit from the EU without a deal”.
Ex-foreign minister Boris Johnson and ex-Brexit Foreign Minister Dominic Raab have said they would want to renegotiate the terms of Mrs May’s exit agreement with Brussels, but would enforce the current October deadline.
Gerard Lyons, co-founder of economists for the Brexit, said today: “I don’t think any of the leading candidates advocated a deal as their plan A.
“You must have a plan B. No deal, whether we want him or not, must be plan “B”.
“The CBI, remember, was under Project Fear three years ago and since the referendum we have seen a million jobs the economy,” he said.
Mr Lyons, a former adviser to Mr Johnson, told the BBC a no-deal Brexit would only be a “springboard” for a free trade agreement.
He said that the challenges for the UK outside the EU would be “better addressed “and that emphasis should be placed on issues such as infrastructure investment and investment to address” economic imbalances”.