The women were forced to swim with piranhas

Police say that while the 19-year-old sister had to swim in a transparent tank, the 16-year-old had snakes draped across her body and suffered bites.

Four members of the family have been freed from what has been described as a "circus of horrors" south of Naples.

Three men have been arrested and charged with holding them in slavery.

The women were paid 100 euros (£78) a week, forbidden to leave the camp and forced to work 15- and 20-hour shifts, according to police.

The Bulgarian family has now been moved to a safe house but their case highlights the plight of people caught up in human trafficking networks in Europe.

The European Union estimates that 500,000 people are affected by trafficking every year in Europe.

In 2006, more than 100 Polish workers were freed from forced labour camps in the Puglia region of Italy where they had been promised seasonal farm-work.