Police in Spain have made a major breakthrough in their investigation of one of the biggest human trafficking rings in Europe.

Sharing some of their findings with the BBC, they reveal Britain's airports are increasingly being used by major trafficking gangs as a gateway to the European Union.

The gangs which operate in Africa, North America, the Middle East and in Europe have trafficked many thousands of people, including hundreds of women who have been forced into prostitution.

Orla Guerin reports from Barcelona, where the investigation is being coordinated.