The Taoiseach, Mr Ahern, welcomed the Northern Secretary's invitation to Sinn Fein as a "huge opportunity". Speaking to reporters at Dublin Airport, Mr Ahern said security intelligence on the current IRA cessation showed it was "even better than the previous one".
Mr Ahern said he understood the suspicions of the unionist community, but he hoped that they could recognise the opportunity offered by the talks.
"This seems to be the most complete ceasefire that we have seen, including the 1994 one. And I am sure that they and the people they represent wholeheartedly welcome that. And the opportunity to build on that is an opportunity for them as well as it is for me."
He said Sinn Fein should sign the Mitchell Principles and declare that the party was "moving away from the ways of the past and signing up to the peaceful democratic way into the future".
In a statement, the Minister for Foreign Affairs, Mr Burke, said that all eligible parties should be at the table when political negotiations began next month. "No party should allow the interests of those it represents to go by default. Let everyone at the table hear your case and listen to your concerns, so that we might collectively address them."
The Fine Gael leader, Mr John Bruton, said participants in the talks would have to "recognise that fundamentalist positions will have to be abandoned on all sides".
The Democratic Left TD, Mr Eamon Gilmore, said the party saw the decision as a "significant development which increased the potential for real political progress in Northern Ireland".
