A man was arrested on Monday on suspicion of manslaughter in connection with the deaths of 39 Vietnamese nationals that were found in a refrigerated lorry container in October in Essex in southeast England.
British police said the 36-year-old man, from Purfleet in Essex, remains in custody, media reports said.
The arrest, the latest police move as a result of an ongoing investigation into the deaths of 31 men and eight women, came after Christopher Kennedy, 23, was charged on Sunday with human trafficking offences. He is from County Armagh in Northern Ireland.
Kennedy was arrested in the early hours of Friday morning on the M40. He appeared in Chelmsford Magistrates' Court on Monday and spoke only to give his name, age, address and nationality.
Also on Monday, Maurice Robinson, the 25-year-old British truck driver who was the first to be arrested after the incident, admitted being part of an international smuggling ring.
He was charged with the manslaughter of all those on board the lorry as well as with allegations of people trafficking, breaking immigration laws and money laundering.
His charges related to a 17-month conspiracy running between May 2018 and Oct. 24 this year.
Another man from Northern Ireland was charged with human trafficking offences last week.
Meanwhile, extradition proceedings have also been launched in Ireland to bring Eamonn Harrison, 22, from Mayobridge in Newry, Co Down, to the UK, the media reports said.