The chief executive of the industrial plant at the centre of the toxic sludge spill in Hungary has been taken in for questioning by police.
The arrest of Zoltan Bakonyi was announced by the PM Viktor Orban.
Mr Orban also said the company would be temporarily nationalised and that those responsible for the disaster should bear the financial consequences.
Seven people have so far died from the 4 October spill near Ajka in the west of the country.
About 150 people were also injured after up to 700,000 cubic metres (24.7m cu ft) of toxic by-product from the production of aluminium burst from a storage reservoir.
A team of experts from the European Union is on the scene looking at how to lessen the impact of a further rupture in the reservoir, which officials say is now inevitable.
A protective ring of rock and earth is hurriedly being built to try to beat the expected next torrent.
The EU’s civil protection unit is also helping to assess the contamination to the region’s ground water and soil. They are also examining the potential airborne hazard as the toxic mud dries out.
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