Ireland will be "firmly" on the side of the EU and will not act as a "proxy" for the UK despite our close ties, Foreign Affairs Minister Charlie Flanagan has said.
The minister dismissed the idea that Ireland is too close to the UK after Prime Minister Theresa May described our "special relationship" in the letter which triggered Article 50.
Mr Flanagan said: "Ireland will not be a proxy for the UK in these negotiations. Ireland will be firmly on the side of EU 27.
"Having said that there are issues of a special nature that we will be able to bring to the table in the context of our relationship with Britain."
In the letter which was delivered to European Council President Donald Tusk yesterday, Mrs May wrote that she does not want Brexit to "harm" their nearest neighbours.
"The Republic of Ireland is the only EU member state with a land border with the United Kingdom.
"We want to avoid a return to a hard Border between our two countries, to be able to maintain the common travel area between us, and to make sure that the UK's withdrawal from the EU does not harm the Republic of Ireland," she wrote.
"We also have an important responsibility to make sure that nothing is done to jeopardise the peace process in Northern Ireland, and to continue to uphold the Belfast Agreement."
Mr Flanagan welcomed the specific reference to Ireland, but added: "I feel personally very sad. I think the British have made a very bad decision."
Meanwhile, Finance Minister Michael Noonan yesterday discussed the fallout from the triggering of Article 50 with the UK Chancellor of the Exchequer Philip Hammond.
"I reminded Chancellor Hammond that Ireland remains fully committed to our membership of the EU and we will be negotiating as part of the EU 27 in the negotiations ahead.
"We have strong relations with the EU and the UK and we are intent on maintaining both," Mr Noonan said afterwards.
Fianna Fáil's Brexit spokesman Stephen Donnelly said the triggering of Article 50 was "a wake-up call for the Government".
"The stakes for Ireland are rising, with both the UK and EU talking up the prospect of a disorderly Brexit.
"If a 'cliff' is reached in two years, with no agreement in place for the on-going relationship between the EU and UK, we are looking at enormous economic, political and social ramifications on the island of Ireland," he said.
"The Taoiseach will lay out Ireland's priorities to other EU Council members next month. And yet, with Article 50 triggered, we remain no clearer on how the Government hopes to shield the Irish economy from the shocks this event may cause."
Mr Flanagan also expressed concern that Brexit negotiations are set to begin at a time when Northern Ireland is without a government.
He said being a voice for the North "will now fall to us".
In the UK parliament, Mrs May played down talk that Brexit is moving a united Ireland closer.
She said her government "will never be neutral" on the future of the North.
"We are of course, within that, fully committed to ensuring that the unique interests of Northern Ireland are protected and advanced as we establish our negotiating position.
"Our position has always been clear that we strongly support the Belfast Agreement, including the principle of consent that Northern Ireland's constitutional position is a matter for the people of Northern Ireland to determine," she said.