Four people are in now custody after the deaths of 39 people in a truck in Essex in England on Wednesday.
UK police arrested three more people yesterday, including a married couple and a 48-year-old man from Northern Ireland.
The couple, with an address in Warrington, are believed to be Irish while the man was arrested at Stansted Airport.
A 25-year-old man from County Armagh also remains in custody in relation to the deaths.
Police are continuing efforts to identify the victims, believed to be from China and Vietnam.