The 16 people found in the back of a lorry on a ferry to Rosslare in Co. Wexford have spent the night in a reception centre in Dublin.
They spent up to 12 hours in the trailer of an articulated tractor unit before being discovered by staff on the Stena ferry which was en route from Cherbourg to Rosslare.
Superintendent Jim Doyle said all 16 are in excellent health.
Mr Doyle said: "I understand at this time that all the males are adult and Middle-Eastern, however, gardaí have yet to confirm if one male is a juvenile.
"That particular lorry, tractor and trailer are owned by a local Irish-based company, the owners are cooperating fully with the investigation.
"The driver is a male, believed to be in his 50s, he is also a long-time employee of the company and he is also assisting us with our inquiries."
Pippa Woolnough, from the Immigrant Council of Ireland, said the incident shows how desperate people are to flee their homeland.
Ms Woolnough said: "It is very upsetting to hear that people are feeling that their only option is to put their lives in danger to travel either away from danger or persecution or they have been forced or coerced into this situation.
"So I am very glad to hear the Taoiseach saying that he is taking a humanitarian approach first."
