The toll rose to four dead, six missing and at least 120 people injured after a reservoir failed Monday at the Ajkai Timfoldgyar plant in Ajka, a town 100 miles (160 kilometers) southwest of Budapest, the capital.

Several hundred tons of plaster were being poured into the Marcal River to bind the toxic sludge and prevent it from flowing on, the National Disaster Management Directorate said.

So far, about 35.3 million cubic feet (1 million cubic meters) of sludge has leaked from the reservoir, affecting an estimated 15.4 square miles (40 square kilometers), Environmental Affairs State Secretary Zoltan Illes told the state news wire MTI. [ YAHOO NEWS ]