The four Catholic Archbishops have asked people to observe Friday as a "day of solidarity" for the victims of the tsunami disaster.
The solidarity could take the form of fasting, reflection and generosity, said Dr Seán Brady, Archbishop of Armagh and Primate of All Ireland.
He said the disaster was "upsetting beyond words, especially when set against the happy celebration of Christmas".
"We must now do all we can to support the survivors and help them in the reconstruction of their lives," Dr Brady said.
"We are therefore calling on the faithful to observe this Friday as a day of solidarity with the victims."
He said people should undertake an exercise of fasting appropriate to their condition. Families and parishes should take time to come together and pray for the victims and survivors of the tidal wave.
Dr Brady also asked congregations to be generous this weekend as special collections would be taken up at Masses across the country for Trócaire's emergency appeal.
The Taoiseach, Mr Ahern has called for the observance of three minutes silence in memory of the victims at 11 a.m. tomorrow. Mr Ahern has asked all public buildings to fly the national flag at half-mast tomorrow.
The initiative comes from the Luxembourg presidency of the European Union which has called on all EU member states to observe this silence.
"It is essential that we mourn the victims of this horrific event. It is also essential that the world community as a whole assists the survivors in rebuilding their communities and their lives," Mr Ahern said.
Four Irish people are still on the Department of Foreign Affairs "high risk" missing list. They are Ms Eilís Finnegan and Ms Lucy Coyle from Dublin, Mr Conor Keightley from Tyrone and Mr Michael Murphy from Wexford.
Non-governmental organisations will meet the Taoiseach and the Minister for Foreign Affairs, Mr Dermot Ahern, at Government Buildings this afternoon to discuss how best the Government donation of €10 million should be spent.
Mr Tom Arnold, Concern chief executive, said he would be urging that the aid effort be co-ordinated, both at Irish and at international level.
He said the UN had a crucial role to play in ensuring that a co-ordinated approach was taken. "I'm not confident that there has been sufficient urgency to make it happen," Mr Arnold said.
Trócaire would be calling on the Government to take the opportunity to press the Indonesian government to resume talks with the freedom movement in Aceh, said Ms Mary Healy, Trócaire's emergency co-ordinator.
Until the tsunami, nobody was allowed into this heavily militarised part of Indonesia, Ms Healy said.
Trócaire expected to be working in Indonesia for a long time, given the devastation it was witnessing, she said "We hope that the Irish Government will be in it for the long haul too."
Meanwhile, Mr John O'Shea, GOAL's chief executive, said he would be using today's meeting to urge the Taoiseach to deploy Irish army personnel to South East Asia.
He said aid agencies did not have the capacity to deploy cranes or cross land where bridges had collapsed but army personnel did.
Dr Brian Scott, Oxfam Ireland director, said his organisation would be calling on the Government to review its aid budget and meet earlier promises.
