"It's just not possible" to check every shipping container that enters this country for people, the head of a human trafficking charity told Good Morning Britain.
Andrew Wallis, chief executive of Unseen, said the only way to prevent cases like that of the 35 Afghani Sikhs found in a container at Tilbury Docks is to improve the circumstances for people in "source countries."
Mr Wallis said half a billion containers get shipped around the world every day.
The uncle of dead Afghan immigrant Meet Singh Kapoor says he wanted a better life for his children. Instead his children watched him die.
ITV News has spoken to the translator police used after 35 Afghan Sikhs, including 13 children, were found in a boat in Tilbury Docks.
ITV News has obtained exclusive footage of people, believed to be Afghan Sikhs, being released from a shipping container at Tilbury Docks.