The Bureau recalled that these two sites cover the same waterfall area which extends across the two countries. The Bureau was concerned that, for tourist purposes, eight helicopters now simultaneously overfly the falls causing serious acoustic disturbance in an otherwise natural setting, and that more than 7,000 visitors have registered complaints. The Bureau also noted that local non-governmental organizations are opposing the use of helicopters as an inappropriate activity that contravenes legal air traffic regulations for flights over protected areas. The Bureau requested the Secretariat to convey these concerns to the authorities of Argentina and Brazil and suggest that they co­operate in devising management strategies to control helicopter tourism of the area.