British authorities investigating the death of a migrant inside a shipping container say the victim and 34 survivors are Afghans from the country's Sikh community.
Police initially thought they were Indian.
The group arrived at Tilbury Docks, Essex, a port east of London, on August 16 on a ship from Belgium.
One man was found dead and the others were taken to hospital to be treated for dehydration and hypothermia.
The migrants included 13 children aged between one and 12.
British police launched a homicide investigation following the death of the man.
Belgian police say they are tracing movements of the truck that delivered the container, with the Afghans presumably inside, to a Belgian port on August 15.
Afghanistan's 3,000-member Sikh community has endured a long history of religious discrimination and harassment.