A German court has decided not to prosecute 10 people summonsed over a deadly mass panic at the Love Parade techno music festival six years ago.

Four employees of the event's organizer and six local authority workers had been facing charges including involuntary manslaughter.

The DPA news agency reports that following the decision to drop the criminal proceedings, prosecutors in Duisburg can appeal to the city's higher regional court. No further action can be taken if the appeals fail.

21 people died in the crush in July 2010 in a packed tunnel that was the sole access point to the event in Duisberg.

The tragedy led to the permanent cancellation of the Love Parade festival. Duisberg mayor Adolf Sauerland was voted out of office in a recall election in 2012 following criticism of the council's handling of the tragedy.