Prosecutors had appealed against a 2016 ruling that acquitted 15 people in the case.

This file photo taken on October 8, 2010 shows an aerial view of the village of Kolontar, nearby the Torna stream, some 160 kilometres southwest of the Hungarian capital Budapest, after a wave of toxic red mud of the Ajkai Timfoldgyar plant swept through the village. Photo - AFP This file photo taken on October 8, 2010 shows an aerial view of the village of Kolontar, nearby the Torna stream, some 160 kilometres southwest of the Hungarian capital Budapest, after a wave of toxic red mud of the Ajkai Timfoldgyar plant swept through the village.