British police say they are looking for two brothers from Co Monaghan over the deaths of 39 people in the back of a truck in Essex last week.
Ronan Hughes, 40, and his brother Christopher, 34, are wanted on suspicion of manslaughter and human trafficking, Essex Police said.
"Finding and speaking to the Hughes brothers is crucial to our investigation," said Detective Chief Superintendent Stuart Hooper.
"If you know where they are or have any information about their whereabouts I need you to call my team," he said.
It is understood that the Hughes brothers are originally from Co Monaghan and are living at an address at Leitrim, Tyholland, Co Monaghan.
Essex Police said both men have links to Northern Ireland, particularly Co Armagh.
Gardaí do not have the legal authority to detain the two men.
Garda Headquarters recirculated the appeal for information on the whereabouts of the brothers and gardaí say they are continuing to assist Essex Police with their investigation.
However, they stress they only have the power to arrest and detain people suspected of a criminal offence in this jurisdiction.
RTÉ News has also learned that gardaí have not received any European Arrest Warrants in connection with the investigation into the 39 deaths.
A person can only be extradited from Ireland for the purposes of being charged, not for questioning.
Maurice Robinson, 25, from Craigavon in Co Armagh, has been charged with 39 counts of manslaughter, conspiracy to traffic people, conspiracy to assist unlawful immigration, and money laundering in relation to the incident.
He is due to appear at the Old Bailey in London on 25 November.
Three other people arrested - a 38-year-old man, a 38-year-old woman, and a 46-year-old man - have all been released on bail until November.
Essex Police said gardaí are assisting them with their inquiries and anyone with any information is asked to contact the Garda confidential Line 1800 666 111 or Essex Police on 0044 207 158 0010, the anonymous Crimestoppers line on 0044 800 555 111 or online at https://mipp.police.uk.
Additional reporting: Paul Reynolds, Sinéad Hussey