The Republic of Ireland's opposition leader has said he hopes the UK's European Union referendum result will encourage support for a united Ireland.
Fianna Fáil's Micheál Martin referred to the fact that a majority in Northern Ireland (56%) voted to stay in the EU.
He said the result, in contrast to the overall UK vote to leave, could be a "defining moment".
Mr Martin said a referendum on a united Ireland should be called, if there was evidence of sufficient support for it.
The Fianna Fáil leader made the comments as he delivered the annual John Hume lecture at the MacGill Summer School in Glenties, County Donegal.
He said the strength of the remain vote in Northern Ireland during the EU referendum may show there is a need to "rethink current arrangements".
"It may very well be that the decision of Northern Ireland to oppose the English-driven anti-EU UK majority is a defining moment in Northern politics," he said.
Mr Martin added: "I hope it moves us towards majority support for unification, and if it does we should trigger a reunification referendum."
But he also said the evidence needed to call a referendum on united Ireland was not yet available.
"At this moment the only evidence we have is that the majority of people in Northern Ireland want to maintain open borders and a single market with this jurisdiction, and beyond that with the rest of Europe," Mr Martin said.
Last month, the then Northern Ireland Secretary Theresa Villiers ruled out Sinn Féin's call for a border poll on the reunification of Ireland.
She said: "The Good Friday Agreement is very clear that the circumstances where the secretary of state is required to have a border poll is where there is reason to believe there would be a majority support for a united Ireland.
"There is nothing to indicate that in any of the opinion surveys that have taken place.
"Again and again they demonstrate that a significant majority of people in Northern Ireland are content with the political settlement established under the Belfast Agreement and Northern Ireland's place within the United Kingdom."