A senior DUP MP has warned the Republic that it will not be negotiating on Northern Ireland's behalf with the EU.
Jeffrey Donaldson spoke out as speculation mounts that Taoiseach Enda Kenny is giving serious consideration to setting up an all-island forum to plot the way forward following the UK referendum vote to leave the EU.
Mr Kenny's plans have been welcomed by the SDLP and Sinn Fein - but the DUP said the Irish Government cannot speak for Northern Ireland in any forthcoming negotiations.
The contentious EU referendum result is expected to top the agenda at a North South Ministerial Council in Dublin today.
Mr Donaldson said there is no need for such a forum, adding that the DUP will make it clear at today's meeting that the main negotiations with the EU on behalf of Northern Ireland will be undertaken by the UK Government.
"There will be discussions in the North South Ministerial Council, including at Monday's meeting," he said.
"These will include how we continue to work together post-Brexit and deal with issues such as north-south trade and the common travel area.
"There will no doubt be similar discussions in the British Irish Parliamentary Assembly also meeting this week at Malahide.
"These bodies were set up to deal with such issues and we don't need another one.
"We are clear that the main negotiations will be undertaken by the UK negotiating team and we will be part of that through the NI Executive and our presence in Parliament.
"Using these channels we will seek to ensure Northern Ireland gets a good deal."
But SDLP leader Colum Eastwood claimed that the proposed new forum was essential.
"We believe that it is necessary to consider the issues and implications, not least in terms of helping to develop optimum coherence and consensus on how to minimise the adverse economic fallout and ensure growth on the island," he said.
"We must ensure that any border which is erected is only operational around the island of Ireland, not across it.
"This week we have had confirmation that neither the British Government nor the Northern Ireland Executive have put in place contingency plans to deal with the fallout of the referendum result.
"Here on the island of Ireland, we must map the challenges, purposes and priorities that could most affect us, north and south, rather than following the impulses and bad decisions of the British Government."
Sinn Fein president Gerry Adams also welcomed news of the proposed forum.
"Subject to seeing the details of the Taoiseach's proposals, I welcome the commitment to establish such a forum," he said.
"Any such forum must have island-wide participation and involve the Assembly parties, the Oireachtas, the European Parliament and civic society.
"The vote of the clear majority of citizens in the north who want to remain in the EU must be respected and defended.
"The Remain vote brought together unionists, nationalists, republicans and others in common cause on the same platform. Those who campaigned for a Leave vote should also be invited."
Some 56% of voters in Northern Ireland wanted to stay in the EU while 44% opted to leave.
Overall, the UK voted to leave the UK by a slim majority of 52% to 48%.
Close co-operation between police forces in Britain and Northern Ireland and the Garda will be seriously hampered in the future unless the UK can successfully negotiate similar arrangements to those that existed before Brexit.