Hungary is fighting a desperate battle to stop a tide of toxic sludge from contaminating key waterways following one of the worst ecological disasters to affect the region in recent years...[A] reservoir ruptured at an aluminium plant in Ajka...burying nearby villages with...caustic alkaline material. Brussels has expressed concern that the sludge could affect countries downriver from Hungary if it entered...the Danube...The clean-up is expected to take at least a year and cost tens of millions of dollars...MAL Rt, the Hungarian Aluminium Production and Trade Company, which owns the plant, initially said the sludge...was “non-hazardous”, according to EU standards. But the government responded angrily to these claims after four people were killed in the floods and scores of locals suffered burns and eye irritation from contact with the red mud, which contains heavy metals...[T]he Danube passes through Croatia, Serbia, Bulgaria, Ukraine, Moldova and Romania before flowing into the Black Sea. Hungary’s national investigative agency has taken over the inquiry into how the reservoir burst...MAL said it believed the corner of the reservoir had slipped on its clay-base and that it could not have detected the “natural catastrophe” or done anything to avert it.