The European Commission President, Mr Romano Prodi, will lead the 20-member EU executive to Dublin on Tuesday for detailed talks with the Cabinet on Ireland's six-month EU Presidency.
The Taoiseach yesterday opened Ireland's Presidency, expressing caution over whether the Union's constitutional treaty can be agreed during Ireland's term but pledging progress in key areas of EU business.
His remarks came as it emerged that the Irish Congress of Trade Unions has urged the Government to abandon its implacable opposition to tax harmonisation in the EU.
The ICTU has warned that countries such as Poland, the Czech Republic and Hungary which will join the EU in May could undercut Ireland's low 12.5 per cent corporation tax rate in an attempt to attract US investment unless the Union agrees guidelines.
Mr Ahern said yesterday that economic reform, justice issues and the improvement of the EU's external relations - particularly with the US - would be priorities.
These issues will be discussed next Tuesday in meetings between himself and Mr Prodi, and between individual ministers and Commission members.
The Taoiseach also confirmed yesterday that he would report to the European Council meeting in March on the prospects for agreement on the EU Constitutional Treaty, following the failure of last month's Brussels summit.
While promising to "make every effort" to reach agreement, he said he could not promise success.
Tax harmonisation is among the issues which could re-emerge during talks on the constitutional treaty. The Government resisted moves towards some limited harmonisation during the recent failed EU treaty negotiations and fiercely defended Ireland's low corporation tax, which is seen by some other member-states as providing unfair competition.
However, in a submission to the Government's Enterprise Strategy Group, the ICTU has warned that low business taxation will not protect Ireland's economy from the increasing economic pressures resulting from economic globalisation. Congress instead has backed limited EU tax harmonisation, warning there was nothing stopping states which would be joining the EU in May from undercutting Irish rates.
The Government should therefore negotiate now with fellow EU states to agree a band of corporation tax rates to apply in the EU, depending upon a country's economic development and peripherality.
"At the end of the day, our judgment is that the Europeans will not wear tax competition indefinitely and it might be better to negotiate a deal now rather than have it forced upon us," according to the ICTU.
Acknowledging that low corporation tax helped to attract foreign investment, the ICTU asked: "But is 12.5 per cent the critical level? Why did we need to go below 16 per cent? Would foreign direct investment still come at 20 per cent?"
In his speech marking the beginning of Ireland's Presidency yesterday, the Taoiseach said the 10 new members joining on May 1st would mark a "profound transformation" of the Union. The EU had succeeded for almost 50 years and "the 10 accession countries, who will formally join us in May, want to be part of this success".
Mr Ahern was speaking at a ceremony in Dublin Castle attended by members of the Government, former Taoisigh and diplomats to mark the start of the Presidency.
He was cautious about the prospect of agreeing the constitutional treaty during Ireland's Presidency. The Government would be motivated by a desire to build consensus. "I cannot promise success but I will promise that we will work very hard to achieve it."
The Tánaiste, Ms Harney, who also attended yesterday's ceremony, said there was a "huge agenda" of issues which could improve the economic competitiveness of the EU.
Mr Ahern said the Government would place particular emphasis on improving EU/US relations, although a hoped-for EU/US summit had still not been confirmed.