BERLIN- German police have thwarted plans by neo-Nazis to attach makeshift bombs to model airplanes and target a gathering of their political opponents, prosecutors in the southern city of Freiburg said on Tuesday.Police seized explosives, detonators and several model airplanes while searching the flats of four suspects and a neo-Nazi venue outside Freiburg last week, they said in a statement.The suspected ringleader of the plot, an unnamed 23-year-old man, was arrested. Last month he was caught throwing a firecracker at a demonstration by anti-fascist groups against a far-right protest in the western city of Dortmund.Police said they also found chemicals, narcotics and a video camera at the sites.