Northern Ireland Deputy First Minister Martin McGuinness has called on the Irish Government to represent all Irish citizens when Brexit negotiations kick in.
On the eve of a major all-island forum on the issue in Dublin, the Sinn Féin chief urged Taoiseach Enda Kenny to fight for people both north and south of the border.
"This forum is hugely important as it represents an opportunity to have an island-wide discussion on the impact of the recent EU referendum," Mr McGuinness said.
"This is not just an issue for the north; it will impact on the entire island and it is vital we deal with it on that basis.
"The Irish Government will have a central role in the upcoming Brexit negotiations when article 50 is triggered.
"The British Tory party can't be trusted to act in the best interests of the people of Ireland.
"It is crucial that the Irish government represents the national interests of all Irish citizens, of the economies north and south, and safeguards the advances of the Good Friday and other agreements."
The Taoiseach will be hosting the all-island discussions on the fallout from Brexit at a day-long conference at the Royal Hospital Kilmainham in Dublin tomorrow.
About 300 politicians, business people, community representatives, academics, civil servants and trade unions are to take part.
Billed as the All-Island Civic Dialogue, Mr Kenny has said the event aims to hear from those affected by Britain's departure from the European Union and to map out the challenges that poses and their potential impact on different parts of society on an all-island basis.
It will focus on the fallout from Brexit and the potential impact on economy and trade, the peace process, the UK-Ireland common travel area, the border and the future of the EU.
A report and recommendations are to be drawn up following the meeting to advise the Government on issues related to the UK's negotiations with Brussels.
All of Northern Ireland's main unionist parties snubbed an invitation to the event.
Stormont First Minister and Democratic Unionist leader Arlene Foster said she had better things to do than listen to a lot of "grandstanding remoaners" and she described the forum as a talking shop.
Relations further soured after Ms Foster, who campaigned for Brexit, also accused Irish officials of poaching investment from Northern Ireland.
A majority of voters in Northern Ireland sought to remain in the EU.