A vote to leave the EU will cause British business competitiveness to suffer, the director general of the World Trade Organisation (WTO) has warned, in a visit to London today.
"While trade would continue, it could be on worse terms," said the WTO chief Roberto Azevedo.
"Most likely, it would cost more for the UK to trade with the same markets - therefore damaging the competitiveness of UK companies."
Britain gets preferential export terms for 60 per cent of the goods it sells abroad, which includes the 47 per cent of its exports that go to the EU and the 13 per cent that go to other countries with EU trade deals.
Azevedo said the implication is that UK exporters would risk having to pay up to £5.6bneach year in duty on their exports.
The WTO boss has previously said that Britain would have to renegotiate its relationship with the rest of the organisation if voters opt to leave the EU on 23 June. Azevedo has also stated that the renegotiations could take years or decades, and today he reiterated that it would not be a simple job.
"Key aspects of the EU's terms of trade could not simply be cut and pasted for the UK," he said.
Azevedo's remarks come as polls continue to show differing lead positions for the Leave and Remain campaigns. A YouGov poll out yesterday showed the Brexiteers pulling ahead, while numbers published today show the Remain camp in the lead.