A total of 3,908 people were refused entry at Irish ports, airports and the Northern Ireland Border in 2017, according to details released by the Garda press office.
Of this number, 768 people claimed asylum while the remaining 3,140 were removed from the State.
The majority of these people would have been held in prisons and Garda station cells while they waited for their passage home, but some may also have stayed at the airport or port if a suitable return trip was available.
This number is down on the year previously, where a total of 4,126 people were refused leave to land, with 398 claiming asylum and 3,728 removed from the State.
The Immigration Act 2004 sets out 11 grounds on which an individual can be refused permission to enter the State, including if an immigration officer believes they intend to work in Ireland but do not have an employment permit.
Other grounds include if the the person has a previous conviction for a serious offence or is not in possession of a passport.
If a person is refused leave to land at an Irish port, the carrier is responsible for returning that person to their port of embarkation.
Brazilian woman Paloma Aparezida Silva-Carvalho, who had previously worked as an au pair for a family in Co Galway, made headlines in July 2017 after she was held overnight at Dóchas women’s prison at Mountjoy because immigration officers did not believe she was coming for a holiday.
She had travelled to Ireland to visit the Muller-Wieland family who she had worked for and had booked her return flight for September.
She described her experience at Mountjoy as “the longest night of my life” and her case raised questions around the appropriateness of the policy of detention in prisons or Garda station cells.
The Department of Justice said last July that works had begun on a dedicated immigration detention centre at Dublin Airport and that it would be completed by July 2018.
However, that deadline has passed and the facilities are still not open.
In a statement to The Irish Times, the Office of Public Works said the construction was due to be completed by the end of 2018.
“The OPW awarded the contract for the renovation and fit-out of Transaer House to PJ Hegarty & Sons on Monday 9th April 2018.
"Works commenced on site on 8th May and are expected to be completed by end of this year. "Transaer House will accommodate a facility for the Garda National Immigration Bureau (GNIB) and a new Garda Station," the statement said.