Hungarian Prime Minister Victor Orban says there's a danger of another big spillage of toxic waste from a chemical reservoir.
At least seven people died on Monday when up to 700,000 cubic metres of red toxic sludge swept through villages after a dam wall failed at the alumina plant in western Hungary.
After visiting the scene, Mr Orban says there are new cracks in another wall, and it would probably collapse soon.
Prime Minister Viktor Orban said it was "very likely" that an entire wall of the reservoir would collapse, releasing a fresh wave of chemical effluent.
Mr Orban said another 500,000 cubic metres of waste could escape if the reservoir wall were breached again.
The BBC reports this would be heavier and thicker than the first spill and would be even more toxic.
More evacuations have been ordered.
Mr Orban said there would be "very severe" consequences for those to blame for the disaster.
River Danube reached
All life in the Marcal river, which feeds the Danube, is said to have been extinguished.
The BBC reports that sludge reached the Danube on Thursday, but Hungarian officials said on Friday that the pH level in the river was "normal", easing fears that Europe's second longest river would be significantly polluted.
Emergency crews have been working to dilute the alkaline content of the spill, adding huge quantities of gypsum and chemical fertilisers to the waters of the Marcal and Raba rivers.
