The Taoiseach, Mr Ahern and the British Prime Minister, Mr Blair and will meet next week to discuss ways of saving Northern Ireland's faltering peace process, government sources in Dublin and London have said.
At issue is the ultimatum delivered Saturday by Northern Ireland's Unionist leader Mr David Trimble, who threatened to quit the province's government along with his ministers unless Republican paramilitary activity ends by early next year.
Made under pressure from party hardliners, Trimble's move has prompted Mr Blair and Mr Ahern to try to set up a new round of talks between Northern Ireland's political parties.
A British government spokesman said that the future of the Belfast Agreement "will top the agenda" at the London talks.
A spokesman for the Department of Foreign said Mr Trimble's statement was a "great cause of concern to us", noting in particular the fact that he has said he and his ministers would no longer take part in North-South Ministerial Council meetings.
He said London and Dublin had until October 25th - the next such council meeting -- to "address the issue".