"I think it's absolutely clear that Britain has a greater voice at the trade table being part of the EU, being part of a larger economic entity,"

"We have no free-trade agreement with the UK so they would be subject to the same tariffs – and other trade-related measures - as China, or Brazil or India," he said.

Ukip trade spokesman William Dartmouth said: "I cannot believe that Mr Froman is suggesting that new tariffs are coming up.