A lorry container where 39 bodies were discovered in Essex may have avoided major ports such as Dover to skirt top security checks into the UK, the boss of a haulage trade association.
Richard Burnett, chief executive of the Road Haulage Association, said the lorry could have travelled from France to Ireland, before getting on a ferry to Wales.
He added that the container appeared to be a refrigerated unit, which could have had a temperature of as low as -25C. He described those conditions as "absolutely horrendous".
The victims, found in the container believed to be from Bulgaria, are thought to be 38 adults and one teenager.
Police launched a murder probe after they were called to the Waterglade Industrial Park in Grays at 1.40am today by paramedics.
Chief Superintendent Andrew Mariner said the lorry driver - a 25-year-old man from Northern Ireland - had been arrested on suspicion of murder.
Mr Brunett claims that the lorry unlikely travelled through a port like Dover but instead came to the UK by a ferry from Cherbourg to Rosslare.
He said the vehicle could have then driven to Dublin and taken another ferry to Holyhead, North Wales before then reaching Kent by road.
"It's highly unlikely that if this vehicle has come from Europe that it's been physically checked," he said.
"Because of the migrant issue at Dover and Calais, you've got far more checks that are taking place there.
"You've got heartbeat monitors, you've got dogs, you've got CO2. Those checks are done as you drive through."
He added: "Cherbourg, because it's a low volume port, you probably won't have the same security measures that they have in Coquelles, Calais, for the high number of vehicles that are stepping through there and that's been one of the main migrant routes historically.
"If this is somebody trying to smuggle a significant number of people through then maybe Cherbourg has been picked because it's a little easier to get through."
Temperatures in such lorry units can also be as low as -25C if frozen products are being transported, causing humans to "lose their lives pretty quickly", Mr Burnett also said..
"It's going to be dark. If the fridge is running it's going to be incredibly cold," he said.
"The only place to go to the toilet is on board the back of the trailer.
"You can imagine if they've been in there for days then there will be faeces, there will be urine."
Irish premier Leo Varadkar said any necessary investigations would be undertaken if it was established the lorry had in fact passed through the country.
“The information that we have so far this morning is very sketchy but there are some reports that the truck may have passed through Ireland at some point,” he said.
“So, obviously we are going to need to get more information and carry out any necessary investigations that may be required.
“But I think everyone’s thoughts in this House this morning are with those who are dead, those who have passed on and their families.
“It is a real terrible and human tragedy, and we will carry out any investigations that are necessary if it’s established that the truck did pass through Ireland.”