The attacks in London on Thursday morning have been strongly condemned throughout Ireland.
Irish President Mary McAleese has expressed sympathy on behalf of the Irish people in a message to Queen Elizabeth.
Expressing her “shock and horror”, she said the attacks served no cause “except the cause of evil”.
“Today, which should have been a day of righteous celebration for Londoners, having successfully won the bid for the 2012 Olympics, has been turned into a day of cruel and vicious waste of innocent human life,” Mrs McAleese said.
“In our world, the espousing of hatred will not resolve our problems but will exacerbate them. I offer my deepest sympathy and solidarity to the families of the bereaved and to all the injured.”
Irish Prime Minister, Taoiseach Bertie Ahern expressed “huge sorrow and sympathy” at the attacks .
“This is terrorism and violence perpetrated against ordinary people . . . It’s just a black mark on society, a devastating blow against people,” he said after a private audience with Pope Benedict XVI.
“This is all wanton violence. What does this all mean, killing innocent people who were probably on their holidays, going shopping around London for the day?”
At least one Irish citizen, architect William Walshe, was injured in the attacks. There are fears for another Irish person who may have been caught up in the attacks.
The Dublin government said gardai were monitoring al-Qaida sympathisers in Ireland as part of a massive international security operation.
The Taoiseach also said he did not believe allowing US troops to use Shannon International Airport had left the country exposed to a greater risk of attack.
Sinn Féin President Gerry Adams also condemned the bomb attacks in London and sent a message of sympathy and solidarity to the British Prime Minister Tony Blair and to the Mayor of London Ken Livingstone.
“On behalf of Sinn Féin I offer my sincere condolences to the victims and the families of those killed and injured and to the people of London,” he said.
Fine Gael leader Enda Kenny said the attacks were a “direct challenge” to an emerging “unity of approach”, and the attackers must not be allowed succeed.
“The people of London, where so many Irish people have made their home over the years, are in our thoughts and prayers as they meet this challenge in the days and weeks ahead,” Mr Kenny said.