Quitting the customs union could generate almost 400,000 jobs in the UK thanks to new free trade deals, a pro-Brexit campaign group has claimed.
Change Britain said the UK could hope to secure trade arrangements with up to eight nations if able to negotiate its own deals by exiting the trading bloc, although Theresa May's government has stressed no decision has yet been made.
However, economist Jonathan Portes has rubbished the figures, accusing the campaigners of attempting to “distort” the facts.
A 2012 study by the European Commission, which found that free trade with eight nations and trading blocs including Japan, China and India would be worth 16,700 jobs for every €1bn of extra EU exports.
Working from the UK's estimated 15 per cent of extra-EU exports, Change Britain said that similar deals would be worth 2,503 new British jobs for every €1bn.
Six of the groups examined in the 2012 European Commission report have already expressed an interest in free trade with the UK, while Change Britain said it was “reasonable to assume” similar deals with Japan and the ASEAN bloc would also be agreed.
In total this would generate 387,580 new jobs, the campaign group said.
Portes, a professor of economics and public policy at King's College and senior fellow at think tank UK in a Changing Europe, said that any trade deals would increase both exports and imports.
“Calculating, as Change Britain does, a speculative figure for the number of jobs created by additional exports while ignoring the jobs lost as a result of additional imports is either deeply ignorant or deliberately misleading,” Portes said.
“Whatever your view on the economics of Brexit, Change Britain are again doing their best to distort the debate.”
However, a Change Britain spokesman hit back: “To calculate the number of jobs that could be created from doing more free trade deals we have used the same methodology as used by the EU Commission in its papers on the benefits of free trade. This is the very institution that Portes is still campaigning in favour of.
“We believe that, outside the confines of the EU's customs union, the UK will be in a strong position to do trade deals across the world, creating opportunities for businesses and hundreds of thousands of jobs. It's a shame that experts like Portes continue to talk Britain down.”