The President, Mrs McAleese, last night described the attacks as a crime against the very foundations of "all our humanity and our hearts".
Speaking on RT╔ radio, the President said: "I'm like every other human being with any scrap of human decency and any scrap of human compassion, I'm watching the pictures and its absolutely unbearable.
"It's just simply unbelievable to be witnessing, actually witnessing, such wanton destruction of human life unfolding right in front of our very eyes.
"It's a crime - it's not just a crime against the American people, it's not just a crime against the American civilisation, its a crime against the very foundations of all our humanity and our hearts, every one of us is looking at it and saying 'We know people who could be there, we have friends who could be there, we have relatives who could be there' and so it's doing what it was designed to do, it's spreading terror and fear and panic as it was intended to do, to stop us in our tracks and to show us just how low, how utterly unbearably, unbelievably low human beings can sink in their hatred for one another.
"I think our response to that is and has to be to stand shoulder to shoulder with our American brothers and sisters."