There is a serious risk that elections in Europe will be targeted by terrorists, the Dáil was warned during a debate on last week's European summit in Brussels.
Former taoiseach Mr John Bruton said it was not the case that the Spanish people were bombed into voting its government out of office by al-Qaeda.
"But the bomb brought out voters who would otherwise have stayed at home. There is a risk that will be repeated" and terrorists would target elections.
During the debate which also dealt with the new European constitution and elements including qualified majority voting, Mr Bruton favoured simple majority voting.
He said it was "important to recognise that comprehensive EU legislation was needed to address cross-border crime. That would not happen if the unanimous agreement of all 25 member-states was required."
The Taoiseach, Mr Ahern, who introduced the debate, said the EU faced a period of uncertainty and challenge.
"In face of this uncertainty we need to forge agreements. We need to show we are doing everything possible to protect our populations from terrorist threats like those in Madrid.
"We need to move forward our economic agenda, and create more and betters jobs."
He was hopeful that the new constitution could be agreed before the EU and local elections in June. He warned, however, that the scale of the Madrid attacks demanded a rapid and real response, and that was why the Irish presidency drafted a Comprehensive Declaration on combating terrorism. It underlined that "we are at one in the EU in our determination to face down the terrorist threat".
However, the Fine Gael leader, Mr Enda Kenny, accused the Taoiseach of hypocrisy with his "preaching to his counterparts on the need to ratchet up our fight on terror" given that "we have important legislation on terrorism languishing in the justice committee for over a year, with no sign that the Government intends to progress it".
He also demanded that Irish nuclear experts should have access to Sellafield given the threat of terrorist attack.
Europe needed a new constitution but a "good constitution", the Labour leader, Mr Pat Rabbitte, warned. "What must now be avoided by the Inter-Governmental Conference and presidency is a draft based on horse-trading from the point of view of various national interests, conducted in secret and to the detriment of the precepts of good constitutional drafting as well as at the expense of what was achieved at the convention".
Mr Aengus Ó Snodaigh, Sinn Féin's foreign affairs spokesman, said the Government "is rushing to conclude negotiations on a fundamentally flawed draft treaty in the interests of enhancing its prestige within the EU.
"In the process it has sacrificed transparency and democratic accountability to the Irish electorate, and has also abdicated its responsibility to ensure that the treaty protects Irish interests, the rights of all small nations, and the rights of neutral member-states."
Mr John Gormley, the Green Party president, questioned why the Government had agreed to include the EURATOM Treaty which sustained the EU's nuclear industry "as part of a protocol attached to this treaty". This was "an important issue".
Ms Marian Harkin (Ind, Sligo-Leitrim) expressed concern about the possibility of "unacceptable compromises" in agreeing the new EU treaty.
Irish people barely voted Yes to the Nice referendum, and the prospect of changes in foreign and justice policy would increase concern among the electorate.