The 39 people found dead in the back of a lorry in Essex were all Chinese nationals, it has been reported.
Police have searched two addresses in Northern Ireland connected to the driver - 25-year-old Mo Robinson from Northern Ireland, as the National Crime Agency works towards identifying "organised crime groups who may have played a part".
He remains in custody for questioning on "suspicion of murder".
It comes as Belgian authorities continue to investigate the journey of the lorry where the bodies were found.

Tehran reviewing latest US response as Trump suggests he can wait
Philippines vows to arrest fugitive senator wanted by ICC
UN condemns Israeli decision to establish military facilities in East Jerusalem
Canada PM Carney says Israel's treatment of Gaza flotilla members is 'abominable'
Tankers exit Hormuz as Trump, Vance talk up Iran deal prospects
