The toxic red sludge flooding through Hungary has reached the River Danube, sparking fears the spill could pollute other European countries.
Four people have already died and at least 120 are injured after a resevoir containing waste from an alumina factory burst.
Prime Minister Viktor Orban visited Kolontar, one of the worst affected areas, on Thursday and said there was no point in even removing the rubble from part of the village as it was impossible to live there again.
He said: "It is difficult to find the words. Had this happened at night, everybody would be dead."
He also reiterated that the "catastrophe" could not have been due to natural causes: "This is an unprecedented ecological catastrophe in Hungary. Human error is more than likely. The wall of the reservior did not disintegrate in a minute. This should have been detected."
The flood, estimated at about 700,000 cubic metres, swept cars off roads and damaged bridges and houses.