Legal immigration into the State is running at about 20,000 people a year, the Labour leader, Mr Ruairi Quinn, told the Dail.
The people were, for the most part, returning Irish exiles, members of the European Union or American and Australian students, he said.
"Their place in the software belt around Dublin, Cork and Limerick is a phenomenon we are becoming increasingly aware of. Buying a cup of coffee in this city, for instance, would be practically impossible if it was not for these new labourers who are doing here what young Irish people have always done and continue to do abroad.
"If the economy is to continue growing at the pace it is, then it is important that it continues to draw this reserve pool of labour. By and large, these immigrants are well educated, skilled and English speaking."
Mr Quinn, who was speaking during a debate on the recent European Council meeting in Tampere, criticised the "tardiness" of the Government's decision that asylum-seekers should be distributed around the State.
The Taoiseach, Mr Ahern, who opened the debate, said the Tampere meeting was the first occasion that heads of state and government dedicated a summit to justice and home affairs.
With the adoption of economic and monetary union, the completion of the single market and the resulting freedom of movement across the internal borders of the union, it was almost inevitable that the next challenge for the EU would be to accelerate the process of convergence in the justice and home affairs area, he added.
