Negotiating new trade rules after Brexit could take "decades" for Britain, the head of the World Trade Organisation has warned.
Roberto Azevedo told Reuters that Britain's rights at the WTO would be in a "vacuum" upon leaving despite pro-Brexit campaigners claiming Britain could settle quickly with the EU to keep trade operating.
“I don’t see how just negotiating with the EU is going to obviate the necessity to establish what the parameters are between the UK and all other WTO members,” Azevedo said.
Asked how long such a process could take, he said: "It could be a few years, it could be decades. But our experience suggests that to expect smooth sailing and quick results would be a high-risk bet."
Pro-Brexit campaigners have largely argued that Britain would be able to swiftly broker new trade deals on advantageous terms with the EU, the US and China as the world's fifth largest economy.
Mr Azevedo warned that lengthy talks with the WTO would require the involvement of Brussels as well as Britain.
"It is very likely that both the EU and the UK will have to negotiate with all WTO members," he said.
The EU has still not yet finalised its WTO rights after expanding to 28 member states.