Theresa May must abandon her plans for free trade deals with the rest of the world in order to get a Brexit deal, the EU's chief negotiator Michel Barnier said yesterday.
Speaking in Brussels, Barnier said a full customs union between the UK and the EU would solve the controversial Irish backstop issue as no new checks would be needed on goods crossing the border on the island.
Such an arrangement would all but end May's chances of securing free trade deals with other countries.
Barnier also hit out at May's post-Brexit plan to keep the UK aligned to the EU on goods but not other areas as it would give British business "a major competitive advantage" over its European counterparts.
Commenting on the Irish backstop, Barnier said the EU's plan to keep Northern Ireland in the Single Market and customs union would help keep the border invisible - a goal of both sets of negotiators.
He said: “The future relationship itself might mitigate the checks and even make some unnecessary.
"For instance a veterinary agreement between the EU and the UK would mean less frequent inspections of live animals.
"And we are still open – we are still open – to the idea of having a customs union with the UK. Such a customs union would eliminate an important part of customs checks.”
May has ruled out any agreement which could see customs or regulatory barriers being erected between Northern Ireland and mainland Britain.
Despite his calls for major shift in the UK's negotiating position, Barnier claimed a Brexit deal could be agreed by next Wednesday's European Council summit.