The Taoiseach has told American companies in Ireland that they pay relatively little tax and that it would be difficult to consider giving any further tax breaks to multinationals.

Mr Ahern was speaking at a lunch organised by the American Chamber of Commerce in Ireland and responding to a call by its president Fraser Logue for further tax breaks to be given to workers in high-technology industries.

Speaking after the Taoiseach, the chamber's chief executive officer, Joanne Richardson, called on the Government to curb rising stealth taxation, transportation and waste management costs.

Mr Ahern said that American companies had made a significant contribution to the economy and promised to "listen carefully" to their views, but indicated that the Government was unlikely to concede further tax breaks. "We do listen and listen carefully. We've followed most of the low-tax initiatives you've forwarded to us . . . Given you're paying such little tax at present, it might be hard to reduce it more," Mr Ahern said.

American companies are finding it difficult to retain highly trained staff and want the Government to introduce tax credits for older workers willing to acquire new skills through full-time education, according to Mr Logue.

"At the moment, we're suffering from a under supply of graduates and postgraduates. We are dependent on overseas researchers who are mobile and can leave," Mr Logue said.

Ireland needs to entice 30,000 people back into full-time education and retain more of its existing researchers, Mr Logue said.

He called for the introduction of tax credits of up to €50,000 per year for each worker and called on the Government to do more to control housing and energy costs.

"The difficulties facing people coming here in getting set up - in terms of housing costs and energy costs - these must be controlled," he said.

"We have succeeded in transforming our economy into one of the wealthiest in the world," Dr Logue said, "but there is an immediate need to accelerate our efforts to attract higher value-added investments.

"The nature of this investment dictates a requirement to build innovation capability and human capital rapidly at a time when our education system is failing to meet the output and standards of its previous success when it supported a lower-level economy.

"Every positive aspect of our existing investment base, both overseas-owned and indigenous must be accentuated and all strengths including political stability and Government responsiveness promoted," he said.

Over 620 American companies directly employ 120,000 workers in Ireland and support one-quarter of a million jobs indirectly, Ms Richardson said. But the future of these jobs was now at risk from Ireland's high-cost economy.

"Our message to you is that if our cost base is out of line with competitor economies where tax breaks are the same, then when we look to the long term we have to recognise that there is a risk to investment here."

Her remarks came a day after a warning from business lobby Isme that rising costs were leading to company closures and job losses.

"It is vitally important that the root causes of the dramatic increase in production costs witnessed over the last number of years, including Government-controlled costs, are brought under control," Isme chief executive Mark Fielding said on Wednesday.

Today, the Central Bank will host a day-long conference in Dublin addressing the issue of the economy's declining competitiveness.