An Irish woman has been appointed as the first female secretary general of the European Commission.
Catherine Day will replace Irishman David O'Sullivan who becomes the Commission's Director General for Trade.
Taoiseach Bertie Ahern
Taoiseach Bertie Ahern said the appointments were "a great honour for her and for Ireland."
"The fact that one Irish citizen has succeeded another at the top of the Commission is a testament to the high calibre of these officials and their years of distinguished service on behalf of the people of Europe," Mr Ahern added.
"Catherine Day is well known and admired in the EU Institutions, and in the memberstates, for her dedication, commitment and effectiveness in the performance of a number of key jobs in the Commission, most recently as Director General for the Environment.
Minister for Foreign Affairs Dermot Ahern said Ms Day will bring "energy, judgement and vision to her new task".
He said Mr O'Sullivan had been a "first class Secretary General, and has played a key role during testing years for the Union and Commission."
The Commission said the reshuffling of workers was aimed at ensuring the full implementation of the Commission's guidelines on mobility of senior staff management, as well as strengthening management teams in areas where there were particular challenges ahead.