Ministers rule out checkpoints at Irish border after Brexit

Its top priority in talks over the future of the frontier is to avoid a return to the “border posts of the past”, it will declare today.

The EU has suggested new controls could be necessary to maintain the integrity of the European customs union and single market.

But businesses on either side of the 310-mile border have expressed fierce opposition to any imposition of checks.

The move would revive memories of the Troubles, when border crossings regularly became flashpoints for violence.

In a new position paper, the UK will also dismiss the idea of effectively shifting a customs border to the Irish Sea by introducing checks at ports and airports.

It will argue that creating such a barrier between Northern Ireland and the rest of the UK was “not constitutionally or economically viable”.

Dublin welcomed the plans while warning that maintaining peace in Northern Ireland could not become a bargaining chip in Brexit negotiations.

The document argues that there might be no customs implications at all for road and rail crossings if Britain and EU can clinch an ambitious post-Brexit deal.

If an alternative plan for “highly streamlined” customs checks is implemented, more than 80 per cent of cross-border trade would still be unaffected.

The rest – involving bigger companies –would be covered by a special deal for “trusted traders”.

A government source said: “Both sides needs to show flexibility and imagination when it comes to the border issue in Northern Ireland and that is exactly what our latest position paper will do.”

The source added: “We have some very clear principles. Top of our list is to agree up front no physical border infrastructure – that would mean a return to the border posts of the past and is completely unacceptable to the UK.”

The paper will also reaffirm the UK’s commitment to maintain the Common Travel Area, which allows for free movement of UK and Irish citizens around the island.

It will also include a commitment to uphold the 1998 Good Friday Agreement in “all its parts”.

There have been warnings that Brexit could undermine the Agreement as it was drawn up on the assumption that both the UK and Ireland were EU members.

The Irish government said the paper was “timely and helpful” as it offered more clarity.

A spokesman added: “Protecting the peace process is crucial and it must not become a bargaining chip in the negotiations.”

The Labour MP Conor McGinn of the Open Britain campaign group said: “These proposals on a light touch  border are lighter still on detail.

“They don’t outline how a frictionless or seamless border can be achieved when the UK leaves the EU and won’t reassure anybody about the impact of Brexit on Northern Ireland.”

Tom Brake, the Liberal Democrat Brexit spokesman, said: “It’s clear the government can’t deliver on the Leave campaign’s promise that the border between Ireland and Northern Ireland border will stay as open as it is now.

“Even if they only lead to checks on larger traders, these plans could still severely disrupt trade and have a destabilising impact on the region as a whole.”