Human traffickers have been forcing the women to visit a voodoo priest before they leave their homeland and agree in front of the priest to pay back their travel expenses, the Danish newspaper Nyhedsavisen reported Friday.

"The women don't dare break their contract with the trafficker because they fear that all types of accidents will strike their family because of the voodoo," Dorit Otzen, the head of a Copenhagen women's shelter, told the newspaper.

Otzen said her shelter has often resorted to unconventional methods to help the young women work their way out of prostitution.

In one case they tried to find a voodoo priest in Denmark to cancel the original curse put on the women but it didn't work out.

Volunteers at the shelter have noticed an influx of young prostitutes from Nigeria in recent years.

The country has a strong tradition of witchcraft.