Republicans have urged Spanish authorities to free of a Dundalk republican in Spain on the foot of a German extradition warrant.
Leonard 'Bap' Hardy was arrested at a hotel in the resort of Torremolinos.
He is being sought by German authorities over his suspected role in an attack by the Provisional IRA in Osnabrueck, Germany in June 1989.
Hardy, originally from north Belfast, is believed to have been in Spain for some time.
Hardy is expected to be taken to Madrid pending an extradition case.
Sinn Fein TD Arthur Morgan insisted he should not be held.
The Louth TD said: "Reports indicate that he has been arrested in Spain whilst on holiday on the foot of an extradition warrant from Germany which relates to matters over a decade ago.
"It is my firm view this man should be released and allowed to return home to his family in Ireland without any further delay."
The arrest has come as a surprise following the Provisional IRA's recent announcement ending their armed campaign. Republicans 'on-the-run' from outstanding prosecutions are widely expected to be granted an amnesty following the move.
The Irish Government's Department of Foreign Affairs said it was aware of the arrest. A spokesperson added that officials at the Madrid embassy would be making inquiries.