Sixteen men have been found in a sealed trailer on a ferry sailing from France to Rosslare in the Republic of Ireland.
In a statement, Stena Line said the discovery was made by an employee during a "routine inspection".
It said the people were "reported to be in good health" and were moved to a private passenger lounge on the ship “where their wellbeing is the focus of our employees”.
After the ferry arrived in Co Wexford on Thursday afternoon, Irish police said the individuals were given medical assessments at Rosslare Port.
They say they are all believed to be of Middle Eastern origin, and they are continuing to try to confirm the age of one man "who may be a juvenile".
The articulated lorry was photographed and examined on the ferry and has now been removed for further technical examination.
Gardai said the tractor and trailer are owned by a local, Irish-based company and the owners are co-operating fully with the ongoing investigation.
They said the driver is a man in his 50s, a resident of Ireland for over 25 years, and is co-operating fully with the ongoing investigation.
"Garda Immigration Officers attached to Wexford Garda Station, supported by the Garda National Immigration Bureau are now processing the men under immigration legislation," a statement said.
"After our initial enquiries they will transferred to a reception centre organized by the Reception and Integration Agency where they will be provided for all their welfare concerns.
"This has been a traumatic experience for these men and they are being treated with sympathy and compassion."
An Garda Síochána said the captain of the Stena Horizon ferry had alerted them at around 9.45am on Thursday that a number of people had been discovered in the trailer of an articulated tractor unit on the vehicle deck.
Staff on the ferry, with the assistance of the driver, opened the trailer unit and the 16 men were removed and brought to a private lounge "where they received immediate medical and welfare care".
The ferry arrived in Rosslare at around 2.40pm on Thursday.
Two ambulances and several doctors' cars and police cars drove onto the ship's vehicle deck shortly after it docked in south-east Ireland.
A large police and Immigration Bureau presence was visible around the port.
An Garda Siochana appealed for anyone with information on the incident, "no matter how insignificant it may appear", to come forward.
Earlier, a statement from Stena Line 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."