Political reaction: Taoiseach Bertie Ahern has expressed "huge sorrow and sympathy" at the attacks in London yesterday.
"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.
He queried the mentality of the people responsible and asked who believed that the killing of ordinary people going about their shopping would mean G8 leaders would be forced to change decisions they intended to make.
"What satisfaction do people get out of that? Will this mean that the G8 leaders will make a different decision than they would have made yesterday? It won't," Mr Ahern said.
"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?"
President Mary McAleese has said that yesterday's terrorist attacks on London served no cause "except the cause of evil".
In a message to Queen Elizabeth expressing sympathy on behalf of the Irish people, Mrs McAleese also expressed her "shock and horror".
"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."
The President also telephoned the British ambassador, Stewart Eldon, yesterday morning.
Tánaiste Mary Harney condemned the attacks as "a callous attempt to destroy innocent human life". She expressed "horror and revulsion at today's series of barbaric attacks on the London public transport system".
"While the full details are still unfolding, it is clear that these appalling attacks were perpetrated in a truly horrific manner, and designed to inflict maximum injury to innocent members of the travelling British public."
Fine Gael leader Enda Kenny sent a message of sympathy to British prime minister Tony Blair yesterday morning.
"The timing of this outrage is clearly designed to undermine, and distract from, the efforts of the G8 as they focus tackling the issue of global poverty," Mr 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.
Labour Party leader Pat Rabbitte condemned the bombs as "despicable". They would "repel and horrify anyone with any shred of decency or humanity".
"All democrats must stand firm in the fact of such terrorist attacks, and there must be the greatest degree of co-operation possible between all governments to ensure that those responsible are brought to justice," Mr Rabbitte said.
Green Party leader Trevor Sargent said he was deeply shocked at yesterday's events.
"I have contacted the British ambassador and . . . the English Green Party to convey our shock and express our solidarity with the victims and all those bereaved, injured and traumatised by the unpalatable cruelty of these explosions," he said.