The Taoiseach is making his first official trip to Belfast
Leo Varadkar says time is running out for Northern Ireland in the Brexit negotiations.
He was speaking at Queen's University during his first trip to Belfast as Taoiseach.
His keynote speech touched on several issues surrounding Britain's exit from the European Union.
He made reference to crucial areas including the need to maintain the Common Travel Area, the benefits of a lasting peace in Ireland and the benefits of cross-border co-operation.
In reference to the Brexit talks, Mr Varadkar said: "For our part, the Irish Government will discharge our responsibilities as co-guarantors of the Good Friday Agreement.
"We will do all we can, in Brussels, in London and in Dublin, to achieve the best outcome for everyone on this island - to protect our peace, our freedom, our rights, and our prosperity."
"Today we need an answer to the question, of who we - and others in Europe - talk to in Belfast?
"Who will speak for Northern Ireland and her 1.8 million people? Time is running out, and I fear there will be no extra time allowed.
"It will come as no surprise to anyone here that I do not want there to be an economic border on our island nor do I want one between Ireland and Britain."
"It is at the very heart of the Good Friday Agreement - the right of the people of Northern Ireland to be British, or Irish, or both.
"And, of course, the right to be European.
"And, after Brexit, those rights remain, making this part of Ireland and this part of the UK, truly unique and one that will need unique solutions if we are to preserve and protect all that we've gained."
Mr Varadkar also suggested some solutions to any potential Brexit pitfalls.
"If the United Kingdom does not want to stay in the Customs Union, perhaps there can be an EU-UK customs union.
"After all, we have one with Turkey. Surely we can have one with the United Kingdom?
"If the UK does not want to stay in the Single Market, perhaps it could enter into a deep Free Trade Agreement with the EU and rejoin EFTA of which it was a member prior to accession."
"The challenge in our generation is Brexit. The Brexit negotiations are well underway in Brussels. And, to quote Michel Barnier, the clock is ticking."
Mr Varadkar also warned that large challenges remain.
"Every single aspect of life in Northern Ireland could be affected by the outcome - jobs and the economy, the border, citizens rights, cross border workers, travel, trade, agriculture, energy, fisheries, aviation, EU funding, tourism, public services, the list goes on.
Concluding his speech to the packed crowd, Mr Varadkar added: "At a time when Brexit threatens to drive a wedge between north and south we need to build more bridges and fewer borders."
The Taoiseach will meet 26 other leaders at European Council in October to discuss if sufficient progress has been made on key issues to allow the Brexit negotiations to proceed to the next phase.
"Those three key issues are citizens’ rights, the financial settlement and issues relating to Ireland. It will be a historic meeting for this island", he said.
This afternoon he met with political leaders in the North, including DUP leader Arlene Foster.
After the Taoiseach's meeting with a Sinn Féin delegation, Gerry Adams said: “I told Mr Varadkar that in Sinn Féin’s view designated special status for the North within the EU is the most effective way to defend the Good Friday Agreement, and to ensure that the two economies on the island of Ireland are protected during Brexit.
“I reiterated to Mr Varadkar Sinn Féin’s commitment to the re-establishment of the political institutions. But I made it clear that they must be on a sustainable basis. The Irish and British governments have a key role to play in this."
The meetings came after an Oireachtas committee report examined the prospect of a United Ireland.
Of the 17 recommendations by the committee, one is the need to establish a New Ireland Forum to set a pathway to achieve the peaceful unification.
While a submission to the report from Dr Kurt Hubner of the University of British Columbia showed a reunification scenario with a boost of €35.6bn over eight years to an all island economy.
Mr Varadkar will also attend a breakfast at Belfast Pride on Saturday morning.