The second-highest official in the Department of the Taoiseach is leaving the post with a view to returning to the Department of Foreign Affairs.

Geraldine Byrne Nason has been second secretary general in the department since July 2011, four months after Enda Kenny took of- fice. She will continue in this role until June. Her medium-term career plan was always to continue her career with a foreign posting, it is understood.

The Government spokesman confirmed Ms Byrne Nason was moving, saying Mr Kenny had paid tribute to her work. “She was a pivotal figure in the fiscal treaty referendum campaign and throughout Ireland’s EU presidency,” the spokesman said.

Ireland held the EU's rotating presidency in the first six months of 2013. This was followed by the campaign to exit the bailout last December.

Ms Byrne Nason has responsibility for the co-ordination of European policy. She also supports the work of the Economic Management Council, at which Mr Kenny's sets fiscal policy with Tánaiste Eamon Gilmore, Minister for Finance Michael Noonan and Minister for Public Expenditure Brendan Howlin.

Ms Byrne Nason was deputy permanent representative in Ireland’s permanent diplomatic mission to the the EU, based in Brussels, before her appointment at Government Buildings.

She has also served in Ireland's diplomatic missions to the UN and the Orga- nisation for Security and Co-operation in Europe.