Gardai are holding the truck in which 16 people were found on a ferry today.
It has also emerged that the captain of the Stena Line ship informed gardai of the discovery at 9.45am this morning.
Some 16 people were found in a sealed trailer on board the ferry, which left Cherbourg in France at 9pm on Wednesday.
Gardai and emergency services met the ferry at Rosslare Europort in Co Wexford this afternoon as it docked at 2.40pm.
The people were discovered in a sealed trailer of a lorry during a routine inspection.
They are said to be "in good health" and are receiving medical assistance and assessments.
Gardai will soon carry out an assessment on their immigration status.
The driver and owners of the truck are now assisting gardai with their probe into the find.
A Garda statement this afternoon read: "An Garda Siochana at Wexford Garda Station are currently investigating potential breaches of Immigration Legislation which may have occurred on board a Stena Line Ferry travelling from Cherbourg, which arrived in Rosslare today at approximately 2.40pm.
"At approximately 09.45am today 21 November 2019 the Captain of the Ferry alerted Gardai that a number of people had been discovered in the trailer of an articulated tractor unit on the vehicle deck.
"All the individuals appear in good health and are currently receiving medical assessments on arrival at Rosslare Port. Garda Immigration Officers attached to Wexford Garda Station, supported by the Garda National Immigration Bureau (GNIB) will carry out an assessment on the immigration status of all the persons.
"An Garda Siochana are now investigating all the circumstances of this incident.
"The Articulated Truck involved in this incident has been detained.
"The driver and the owners of the articulated vehicle are assisting An Garda Siochana with our enquiries.
"An Garda Siochana is making no further comment at this time.
"Any person with any information in relation to this incident, no matter how insignificant it may appear, is asked to contact investigating Gardai at Wexford Garda Station 053-9165200, the Garda Confidential Line 1800 66 11, Crimestoppers 1800 25 00 25 or any Garda Station."
In a statement earlier, Ian Hampton, Stena Line's chief people and communications officer, said an employee discovered the people during a routine inspection.
He said: "During the Stena Horizon's 9pm sailing from Cherbourg, France, to Rosslare in the Republic of Ireland on Wednesday November 20, one of our employees during a routine inspection discovered 16 people in a sealed trailer on the vehicle deck.
"All the individuals are reported to be in good health and have been moved to a private passenger lounge on the ship where their wellbeing is the focus of our employees.
"Stena Line has alerted security and immigration officials in Rosslare so as the necessary arrangements can be made for the group on the vessel's arrival in Rosslare.
"The vessel is scheduled to arrive at approximately 3.30pm today."
