The Immigrant Council of Ireland is concerned a detention centre at Dublin Airport could be over-used.
Work is due to begin in September on the facility which will hold people who are due to be deported.
Up until now, people have been detained in the prison system which the UN Committee on Torture has condemned.
The ICI's Pippa Wilnough does not see the need for remanding anyone in any circumstances.
"Detention is a very last resort, you can't deprive people of their liberty," she said.
"Any nation state has the right to refuse people to land and the rules are people should be returned on the next available flight so really there should be no cause for detention."