Perpetrators of stalking often go unpunished, the German victim support organisation Weisser Ring said Friday as it presented details of its “No Stalk App”.

The app has been downloaded about 20,000 times, Joerg Ziercke, who heads Weisser Ring, told dpa on Dec 25.

"But that's not enough," Ziercke added.

Weisser Ring has noted that some 18,000 to 19,000 stalking offences are registered in police statistics, but only one per cent of them result in convictions. The estimated number of unreported cases is thought to be "huge" - some 200,000 to 300,000 cases.

The app is designed to help stalking victims protect themselves and at the same time collect evidence for law enforcement.

For steps to be taken against a stalker, their persistence needs to be documented. There have to be at least five or six instances of stalking behaviour, Ziercke explained.

With the No Stalk app, victims can record everything immediately on their phone via photos, video and dictated notes.

Each of the records is automatically given a digital location. Time information is immediately encrypted, sent to an external server, and then deleted on the victim's cell phone.

As a result, getting a hold of a victim's cell phone is of no use to the perpetrator, according to Ziercke.

According to Weisser Ring, such evidence gathered with the help of the app can be sufficient to file a complaint with the police.

Stalking is punishable in Germany with up to three years imprisonment or a fine. Bavarian Justice Minister Georg Eisenreich (CSU) recently called for stalking legislation to be tightened.

 - dpa