London police are reporting a rising number of child abuse cases linked to witchcraft and ritual beliefs.

Police said Wednesday 27 cases have been reported this year. The figure represents an increase over the 24 reported in all of 2013 and 19 the year before.

This includes the case of a child being swung around and smacked in the head as part of an exorcism and other youths being dunked in water to rid them of evil spirits.

The Metropolitan Police have launched a training film to educate personnel about the signs of ritualistic child abuse.

Detective Superintendent Terry Sharpe called it "a hidden crime," which happens when a family or caregivers genuinely believe a child has been taken over by evil spirits.