A fifth arrest has been made by police amid an investigation into the deaths of 39 migrants found in a lorry in Essex.
A man in his early 20s from Northern Ireland was detained at Dublin port, the Gardai said.
Police had launched a manhunt for the driver who delivered the trailer to the Belgian port where it started its journey to the United Kingdom on Saturday.
Officers from the Belgian prosecutor's office confirmed: "We're trying to identify the driver," in a statement on Saturday morning.
Authorities in the European country are also working to "track the route of the container" and find anyone responsible for "collaborating with the transport".
The spokesperson confirmed "We would like people to be arrested as soon as possible."
British police are working closely with their European counterparts to discover how and why 39 people died during their journey to Essex port of Purfleet.
Essex Police are investigating lines of inquiry to "establish whether there is a wider conspiracy involved" in the deaths, Detective Chief Inspector Martin Pasmore said.
DCI Martin Pasmore said he had met with the Vietnamese ambassador on Saturday morning as part of efforts to engage with the country's wider community.
He said: "Although we can't speculate at this time on the nationality of our victims, it's clear from everybody that we are getting a large amount of engagement from the Vietnamese population, from communities home and abroad."
He added: "What I've done this morning, is I've met with the Vietnamese ambassador and we are building a really good and rapid rapport."
DCI Pasmore said the ambassador had visited and paid tribute at the civic centre in Grays.
Asked about reports the lorry was part of a convoy of three carrying around 100 people, Mr Pasmore said: "No you're homing straight on to an investigative question. My role is to identify the deceased.
"What I will say is I know the senior investigating officer remains open minded. There are lines of inquiry that are set of course to establish whether or not there are wider conspiracies involved in this and the lines of inquiry are set to identify the wider conspiracy but I can say no more than that."
Officers in Essex are continuing to question four suspects over the deaths.
A 48-year-old man from Northern Ireland was detained at Stansted Airport on conspiracy to traffic people and on suspicion of manslaughter on Friday.
A couple named locally as haulage boss Thomas Maher and his wife Joanna, both 38, were arrested on suspicion of 39 counts of manslaughter and people trafficking on Friday.
The driver of the Scania truck, named locally as 25-year-old Mo Robinson, from Northern Ireland, also remains in custody after he was held on suspicion of murder on Wednesday.
The bodies of eight women and 31 men were discovered in a refrigerated trailer in Grays in the early hours of Wednesday.
Essex Police initially believed all of the dead were Chinese nationals, but the force said at a press conference “this is now a developing picture”.
The BBC said it has been in contact with six Vietnamese families who fear their relatives are among the dead, with some having the smuggling fees repaid.
Deputy Chief Constable Pippa Mills said she would give no more details about the nationalities of the victims until formal identification had taken place.
Post-mortem examinations are due to begin as as all 39 have been removed by private ambulance with a police escort from the port of Tilbury to Broomfield Hospital in Chelmsford.
Detective Chief Inspector Martin Pasmore said on Saturday: "All bodies have now been removed from Tilbury for formal medical examination and identification.
"The identification process will be long due to limited documents found in the trailer."
If the fridge on the hermetically sealed trailer was not running there would be no air coming in, suffocating people inside, according to Richard Burnett, chief executive of the Road Haulage Association.