A German bankruptcy administrator has seized a private Boeing 737 used by Thailand Crown Prince Maha Vajiralongkorn as part of a long-running dispute between the Thai government and defunct German construction firm Walter Bau AG. The aircraft is being held at Munich Airport. The dispute relates to alleged unpaid bills from a 20-year-old contract to build Bangkok’s Don Muang Tollway highway. According to Walter Bau’s bankruptcy administrator, Werner Schneider, he requested the aircraft seizure after growing frustrated at the Thai government’s refusal to settle a €30 million ($42 million) debt that he says has been confirmed by previous court rulings and a 2009 international arbitration panel. “The search for the airplane was very complicated and, of course, had to be carried out in a discreet manner to avoid giving any warnings,” said Schneider. Thailand’s Foreign Ministry said that the aircraft seizure was “highly inappropriate.” A ministry spokesman said, “The Thai authorities have expressed to the German government their great concern over the incident and have requested it to resolve the problem as soon as possible.”