The Minister for Foreign Affairs, Dermot Ahern, has expressed surprise at the severity of the sentences handed down to three Irish men for training Marxist rebels in Colombia.
The three men had earlier been acquitted of the charges.
The three-member Penal Chamber of Bogota's Supreme Tribunal has handed down lengthy jail sentences for Niall Connolly, Martin McCauley and James Monaghan.
Monaghan and Connolly have been sentenced to 17 years and 6 months in prison and McCauley has been sentenced to 17 years.
Earlier this year, Martin McCauley from Lurgan, James Monaghan from Co Donegal and Niall Connolly from Dublin were handed down a lesser sentence for travelling with false identification.
The prosecutor involved in the case appealed the leniency of the original sentences to a three-man judicial tribunal.
The panel of judges then reviewed the evidence and overturned their earlier acquittal on the other charge, that of training guerrillas from the Marxist FARC group.
Arrest warrants have been issued for the three men, who have remained on bail in Colombia.
Mr Ahern said there is still the possibility of another appeal and anything the Irish Government could do would have to be at the end of the legal process.
Sinn Féin MLA Catriona Ruane of the Bring them Home campaign said the verdict was ‘military justice’ which would be fought.
The DUP's Ian Paisley Jnr described it as a very good decision and said it was ‘an early Christmas present by the justice system in Colombia to the people in Northern Ireland’.