The idea of Irish ports of entry being used as proxy frontline border posts for the UK, after it leaves the EU, has met with scepticism from the Opposition.

Fianna Fáil spokesman on foreign affairs Darragh O’Brien said it should be a non-runner.

“The idea that the land border between the EU and the UK could be dealt with by giving Ireland responsibility for policing the UK border seems highly implausible,” he said.

Yesterday, Tánaiste Frances Fitzgerald effectively confirmed the Government was agreeable to Irish ports and airports being used as a frontline to control immigration to Britain.

Ms Fitzgerald said there was "not anything surprising" in the views of Northern Secretary James Brokenshire that both Irish and British governments would work to strengthen Ireland's external borders after Brexit, to tackle illegal immigration into the UK.

Hard border

Such a move would help avoid the re-establishment of a hard border between the North and the Republic on the island.

She said that even in the absence of Brexit, co-operation between the jurisdictions would have continued to combat illegal immigration. “The whole question of security in the ports, as well as our interests, is going to be an area where there is more focus on in relation to the risks of terrorism and security co-operation,” she said.

Sinn Féin MEP Matt Carthy criticised the plans being made by the Government in relation to the post-Brexit scenario.

“Nobody knows what the Irish Government’s plans are, if any exist, and they have allowed the British government to dictate the pace.

Ireland’s interests

“We need to see the Irish Government take up their responsibilities to the Irish people, North and South, and to stop being led by the nose by the Tory Brexiteers, who clearly do not have Ireland’s interests at heart,” he said.

Meanwhile, Fine Gael MEP Brian Hayes has suggested Northern Ireland should be given “associate membership” of the EU after Brexit, with the Irish State paying its annual funding contribution.

Mr Hayes last night said such an arrangement would allow the North the right to trade on full or limited terms into the EU, and not be subject to the tariffs.

He said while the constitutional position of the North was settled and it would remain part of the United Kingdom, he said its trading relationship with the EU and with Ireland could be different.

He said it could be analogous to the current relationship between the EU and Gibraltar, or to Norway’s relationship with the EU.