The German parliament on Thursday adopted a draft law which would increase the surveillance of repeat sex offenders after a known pedophile was convicted of repeatedly raping a teenage girl late last year.

The bill, which must be approved by the upper house of parliament before passing into law, would ensure that sexual offenders placed under closer observation in the years immediately following their release from prison.

A visit to a doctor or a therapist could be made a condition of their release and refusal to attend the appointments could lead to a prison sentence of up to three years.

Under the new law, sex offenders could receive therapy for life instead of the current limit of five years.

Justice Minister Brigitte Zypries said she wanted "the best possible protection" for the children and wives of sex offenders, who are at particular risk.

A plea for help

The law was prompted by the case of Mario Mederake, a 36-year-old laborer previously convicted of sexually abusing a child, who raped a 13-year-old girl more than 100 times after seizing her as she walked to school in the eastern city of Dresden in January 2006.

Mederake would shut the girl in a wooden box when he left the apartment and often filmed himself sexually abusing her.

He was sentenced to 15 years in prison in December last year.

The court in Dresden heard that the girl was only freed by police when she managed to drop a scrap of paper in the street which carried a desperate plea for help and the address where she was being imprisoned scrawled in red pen.