Thirty-nine people are in Garda custody following a major operation to round up foreign nationals who are in Ireland illegally.
So far, five people have been arrested on foot of deportation orders and can be held for up to eight weeks before being repatriated.
Thirty-four people are being held under the 1935 Aliens Act.
They are mostly from Eastern Europe or Africa and are here without having applied for asylum or holding any legal documentation.
The Garda National Immigration Bureau has deported 310 illegal immigrants so far this year, but 2,610 people are currently evading deportation orders in Ireland, according to the Gardai.
But they say that the situation is not out of control, pointing to the fact that 310 people have already been deported by the immigration bureau this year, compared with 365 for all of last year.