The Defence Forces has confirmed that Chief of Staff Lieutenant General Dermot Earley is ill.
The General has been on sick leave for the past three months and his duties are being carried out by the Deputy Chief of Staff, Major General Dave Ashe.
It is believed he has been suffering from a debilitating illness which is still under medical investigation.
General Earley, 62, has been in charge of the Defence Forces for the past three years.
He has another year to serve in the position before retirement.
General Earley is a leading figure in GAA circles.
As a young footballer, he won two All Stars with his native Roscommon.
He later went on to manage both Roscommon and Kildare county teams.
The army statement said the best wishes of the Defence Forces are with General Earley and his family.
