Theresa May has reportedly backed Irish and European Union (EU) politicians and blocked proposals for the UK to be able to unilaterally leave a “customs arrangement” with the bloc and take back control of trade policy after Brexit.

Pro-Brexit Tories have been demanding a time limit to the “Irish backstop,” which will keep the entire UK locked in a “customs arrangement” with the European Union (EU) after Brexit, with claims it could make the UK a permanent rule taker from the bloc.

Northern Ireland’s Democratic Unionist Party blocked at the weekend plans without a clear way for the UK to leave the “customs arrangement” and break free of EU courts and rules.

The party had previously blocked plans to keep only Northern Ireland in the arrangement and divide the United Kingdom with customs checks — a move critics have claimed would turn Ulster into a ‘protectorate’ of the EU.

Now, top EU bureaucrats are indicating they are prepared to offer the Prime Minister an “independent mechanism” by which Britain could trigger a “review” on the customs arrangement and move towards ending them.

The Brexit Secretary Dominic Raab had wanted the UK to be able to pull out of the arrangement unilaterally – but this option was slapped down by Mrs May and David Lidington, the Cabinet Office minister, leaving Mr Raab “furious,” The Telegraph reports.

Simon Coveney, the Irish foreign minister, said Monday: “The Irish position remains consistent and [very] clear… that a ‘time-limited backstop’ or a backstop that could be ended by UK unilaterally would never be agreed to by IRE or EU.

“These ideas are not backstops at all [and] don’t deliver on previous UK commitments.”

However, Leo Varadkar, the Irish prime minister, said that Dublin was open to the idea of a “review mechanism” for the backstop that had been put forward by Mrs May in a telephone call.

UKIP released a statement claiming a “secret” deal had been struck in Brussels and the UK would remain an “associate” member of the EU’s Single Market and Customs Union after Brexit day in March.

UKIP leader Gerard Batten said: “If this turns out to be true then it will be a complete betrayal of the referendum result.

“Only a complete exit from the EU will deliver the result 17.4 million people voted for.

“Only UKIP will continue to campaign for achieving an exit from the EU. UKIP will continue to work to restore Britain’s former status as a fully independent democratic nation state for as long as it takes.”