(ANSA) - BELGRADE, AUG 23 - The Flensburg prosecutor's office has launched an investigation after drones were spotted over the ChemCoast Park Brunsbuettel industrial area in the German state of Schleswig Holstein, in the country's north. The drones are suspected to be Russian and investigators are looking into the hypothesis of "activity by espionage agents". The drones flew over the area, where in addition to a now-decommissioned nuclear plant there is a liquefied natural gas terminal and some chemical plants. (ANSA).