The fragile political settlement in Northern Ireland would face greater instability if the UK votes to leave the EU in David Cameron’s planned referendum, a cross-party committee of the Irish parliament has warned.

As Cameron prepares to outline his plans to change the EU “status quo for the better” to the annual June European summit, the Irish parliament’s joint committee on EU affairs calls for Ireland to be given a formal role in any negotiations.

“Instability in Northern Ireland following a UK exit from the EU could impact significantly on north-south relations,” the committee reports, as it warns that some of the cross-border institutions introduced under the Good Friday agreement could be undermined.

The Irish parliamentarians add: “The ongoing fragility of the Good Friday agreement was referenced. The need to actively engage with our Northern Irish colleagues was highlighted in order to raise awareness of the potential effects that a UK exit from the EU could have on the quality of life of people living north and south of the border, as well as on the border communities.”



It will take us another step closer to addressing the concerns that the British people have about the EU David Cameron

The report, which is understood to reflect the concerns of an Irish government that has established a unit to assess the impact of a British exit, comes on the eve of the prime minister’s first presentation of his reforms plans to an EU summit.

Cameron will set out his demands for Britain to be exempted from the EU’s historic commitment to forge an “ever closer union” of the people of Europe, and for EU migrants to be barred from claiming in-work benefits for four years.

British and EU officials downplayed expectations. The prime minister is due to outline his plans towards the end of the summit dinner on Thursday night, after a lengthy discussion on the Mediterranean migrant crisis. If that discussion overruns, the prime minister may have to wait until the summit resumes on Friday morning.

Cameron, who discussed his plans with the German chancellor in Berlin ahead of a state dinner in honour of the Queen, said: “This is my first European council since the election and it’s the first EU summit where renegotiation of the UK’s relationship with the EU is formally on the agenda. This presents an opportunity to get the negotiation underway and to kick off a process to work through the substance and to find solutions.

“It will take us another step closer to addressing the concerns that the British people have about the EU. And closer to changing the status quo for the better and then giving the British people a say on whether the UK should stay in or leave the EU.”

Downing Street was encouraged when Jean-Claude Juncker, the European commission president, appointed the most senior British official in the commission, Jonathan Faull, to head a new taskforce examining issues relating to the UK referendum. Faull will report to Juncker, who will also be advised by the commission’s Anglophile first vice president Frans Timmermans.

Faull is expected to liaise with officials from the EU’s council secretariat and the prime minister’s senior European adviser Tom Scholar, who will embark on technical discussions lasting several months after the summit.

The council will examine Britain’s demands for treaty change on giving Britain an opt out from the “ever closer union” and on the changes to in-work benefits. Faull will be the key figure on changes that would be introduced through secondary legislation, Merkel’s preferred route.

Cameron will fly from Berlin to Brussels on Thursday morning to allow him to take part in a final round of bilateral meetings with EU leaders. The prime minister had aimed to meet, or at least speak to, all 27 leaders, but it is expected that he will struggle to speak to his Greek counterpart Alexis Tsipras, who is focused on a eurozone summit on the Greek financial crisis that will follow the EU summit.

The impact of Britain’s planned reforms – and the possibility that the UK could leave the EU – was highlighted by the Irish parliamentary committee’s report. It warned that some cross-border bodies could become redundant. The members of Dáil Éireann (equivalent to MPs) and senators said: “The committee also heard that [a UK exit] could also threaten other north-south bodies and would ultimately have a politically destabilising effect on the region, relationships and the Good Friday agreement itself.”

The committee said that a British exit could have a “significant psychological impact on those living near the border,” as it called for the maintenance of the Common Travel Area between the UK and the Irish Republic. Dublin should also be given a seat at the negotiations. “Ireland must be involved from the outset in these negotiations based on the special status of the Irish/UK relationship and that the UK/EU relationship is a ‘vital national interest’ to Ireland,” it said.

• This article was amended on 25 June 2015. Because of an editing error, an earlier version misnamed Jonathan Faull as Vivienne Faull.