Enda Kenny has held talks with the Sinn Féin and DUP leaders
The Taoiseach Enda Kenny is urging parties at the Stormont Executive in Northern Ireland to to "engage together to find a way forward".
Mr Kenny met with Sinn Féin leader Gerry Adams and Mary Lou McDonald at lunchtime Wednesday.
Speaking after his meeting with Mr Kenny, Deputy Adams said: "As co-equal guarantors of the Agreement the Irish and British Governments have a responsibility to defend and implement the Good Friday Agreement.
"The British Government will not do this unless the Irish Government holds them to account.
"The British refusal to fulfil its obligations has to be tackled.
"The Government now needs to engage positively in an ongoing and consistently strategic way with the British Government to ensure the full implementation of the agreement."
Mr Kenny subsequently had phone calls with former Northern Ireland Deputy First Minister Martin McGuinness and former First Minister Arlene Foster.
This followed on from a discussion with British Prime Minister Theresa May on Tuesday night.
A statement from the Department of the Taoiseach says: "He encouraged Sinn Féin and the DUP to engage in efforts to protect the Good Friday Agreement and the institutions established by it, emphasising that this remains the best prospect for progress in Northern Ireland.
"Acknowledging the long and difficult personal journeys that many had travelled, he cautioned against letting the progress made since 1998 unravel.
"He made clear that he would maintain close contact with Prime Minister May, and that they had agreed that the two Governments would support the parties in efforts to resolve the current difficulties."
It comes as Foreign Affairs Minister Charlie Flanagan is to travel to Belfast on Thursday for talks.
There he will meet the Secretary of State for Northern Ireland, James Brokenshire, and continue to engage closely with the parties.
Commenting on the crisis, Mr Kenny said: "The situation we now face in Northern Ireland is very serious.
"The best future for Northern Ireland remains in the full implementation of all aspects of the Good Friday Agreement, respecting its principles and operating its institutions effectively.
"A limited window for dialogue remains and I am encouraging the parties to engage together to find a way forward that delivers on the promise of the Good Friday Agreement and its institutions."