The group of 35 people comprising men, women and children found in a shipping container in Essex on Saturday are Sikhs from Afghanistan, the police said on Sunday, as investigations by Interpol and other agencies into the incident spread to several countries.
The police and the group were being assisted by the local Sikh community. The incident is one of the biggest of its kind in recent years as investigations began into the route the group took through countries and continents, and the role of human trafficking gangs.
Superintendent Trevor Roe of Essex Police said: "We now understand that they are from Afghanistan and are of the Sikh faith. We have had a good deal of help from partners within the local Sikh community in the Tilbury area to ensure that these poor people, who would have been through a horrific ordeal, are supported in terms of their religious and clothing needs."
He added: "The welfare and health of the people is our priority at this stage. Now they are well enough, our officers and colleagues from the Border Force will be speaking to them via interpreters so we can piece together what happened and how they came to be in the container."
A homicide investigation has also begun following the death of one person from the group of 35. The police earlier said that the group was from the 'Indian subcontinent'. They were treated for hypothermia and dehydration in hospitals in Essex and London.
James Brokenshire, immigration and security minister, said the incident was a "reminder of the often devastating human consequences of illegal migration. We know that criminal gangs are involved in what amounts to a brutal trade in human lives. We also know that illegal migration is a Europe-wide issue".
He added: "That is why we work closely and collaboratively with law enforcement and port authorities, in neighbouring countries, to target criminal networks and ensure that the organised gangs behind trafficking and people smuggling can't operate with impunity."
In 2000, 58 Chinese men and women were found suffocated in a lorry that had arrived in Dover from Calais. Next year, eight illegal migrants died in a shipping container which had been unloaded at an industrial estate in Wexford in Ireland after a crossing from Zeebrugge.
Shadow immigration minister David Hanson added: "The tragic death at Tilbury is a stark reminder of the human consequences of the trafficking trade and why we need now to take effective action in the House of Commons to bring this to an end."