EU plan assumes Northern Ireland will stay in customs union

The UK must accept the prospect of Northern Ireland staying in the EU customs union with oversight by the European Court of Justice after Brexit, a draft European commission treaty shows.

The 120-page draft agreement says the fallback position for Northern Ireland under Brexit should be “full alignment with those rules of the [EU’s] internal market and the customs union which, now or in the future, support North-South cooperation”.

The document, reported by the Financial Times, also says: “The common regulatory area shall constitute an area without internal borders in which the free movement of goods is ensured” and that “the Court of Justice of the European Union shall have jurisdiction”.

The document acknowledges that Prime Minister Theresa May and EU officials agreed in December on three scenarios for avoiding a hard border in Northern Ireland. Discussions on the other two scenarios may continue but “this protocol is based on the third scenario of maintaining full alignment with those rules of the Union's internal market and the customs union”, the document said.

The leaked draft agreement is the latest development in an intense debate over whether the UK will break off completely from the EU or be part of some form of customs union after Brexit.

The Labour leader Jeremy Corbyn won the backing of business organisations when he said the UK should remain part of a customs union with the EU. Liam Fox, the Brexit-supporting trade secretary, has said such an arrangement would be a betrayal of Brexit voters and stop the UK doing its own trade deals round the world.