Ireland stands by the UK following the Manchester terror attack, the country's Foreign Affairs Minister has said.
harlie Flanagan said he was shocked and horrified by the killings.
"My thoughts and prayers are with those affected, and we stand by our nearest neighbour, the UK especially due to the strong links between our country and the city of Manchester," he said.
Mr Flanagan said consular staff in Britain are not aware of any Irish citizens caught up in the terror attack. A helpline was being manned in Dublin for anyone with concerns about Irish people affected on +353 1 4082000.
Taoiseach Enda Kenny said he was heartbroken for all those affected by the attack.
"The vile acts carried out in Manchester last night are a reminder of the depravity of the views held by the few," Mr Kenny said.
"Those beliefs have no place in our society.
"My thoughts and prayers are with the victims, their families and all those affected by this atrocity. I am heartbroken for all."
Mr Kenny also offered solidarity from the Irish people to those affected.
Other Irish politicians to express horror at the attack included Fianna Fail leader Micheal Martin and Sinn Fein president Gerry Adams, whose party also suspended election campaigns in Northern Ireland.
Mr Martin said: "To attack a group of young people in such a cowardly way is simply abhorrent to the vast majority of people in Ireland, and I know that the people of Ireland stand in solidarity with the people of Manchester.
"As a parent, I find this attack exceptionally difficult to comprehend, and while details are limited at present, it's clear that whoever orchestrated this attack cares little for basic decency and humanity."
Mr Adams said: "This was a shocking and horrendous attack on children and young people enjoying a concert. Our thoughts are with those killed and with all those who are injured."
President of Ireland Michael D Higgins offered sympathies on behalf of Irish people and wrote to the Queen and the mayor of Greater Manchester Andy Burnham to express condolences.
"This cowardly attack on innocent citizens will have appalled all those who care for democracy, freedom and the right to live and enjoy the public space," he said.
"Manchester has been home to the Irish and so many nationalities for centuries and at this terrible time I want to send the people of this great and welcoming city not only our sympathy but our solidarity."
Ireland's Justice Minister Frances Fitzgerald held talks with the country's police chief, Garda Commissioner Noirin O'Sullivan, in the wake of the concert attack.
She said there is close liaison between Irish security chiefs and UK counterparts about the bombing.
"This savage and shocking attack was aimed at people simply going about their lives, out for a night's entertainment. There have always been close ties between people here and in Manchester and we stand in solidarity with our neighbours in the United Kingdom at this time of great loss," she said.
"While there has been no change to the security assessment here and no specific information about a threat to us, last night's attack is a reminder that no one can be considered immune from those whose hatred of our values drives such evil acts."
Ireland's most senior Catholic cleric Archbishop Eamon Martin sent a message to Bishop of Salford John Arnold.
"Such a violent and brutal attack inflicts terror and long-lasting trauma on children and families and leaves a wound that can only be healed by compassion, love and solidarity," he said.
"We are praying for the dead, the injured and for all affected by the bombing. Such an awful attack challenges us all to resolve personally to build peace, solidarity and hope everywhere. Only in this way can the hearts of those who plan and perpetrate such violent and pointless attacks be changed."
The Union flag was flown over Cork City Hall as a mark of respect to those who died or were injured, the city's council said.
Books of condolences were also being opened in Dublin and Belfast for people to pay personal tributes.