The federal prosecutor's office said in a statement on Wednesday that an 'investigation is actively ongoing.' Belgian media reported that several hours of video was filmed near the home of a man thought to be a senior official at the Mol nuclear waste facility in the Flanders region. The house of the unidentified man was apparently filmed from a nearby wood. Prosecutors declined to confirm that information or provide details. Security services have long feared that extremists might get their hands on radioactive material. It comes as a cloud hangs over some Belgium's nuclear plants after a number of unplanned shutdowns.