The Hungarian government announced that it would not seek financial assistance, but it has identified an immediate need for 3-5 experts with strong field experience of handling toxic sludge.
The European Commission announced that since the disaster occurred, on 4 October, its Monitoring and Information Centre (MIC) has been in close contact with the Hungarian authorities to gather information on the incident and was prepared to react quickly should Hungary table a request for support.
The MIC has already communicated the request to the 31 countries that participate in the EU Civil Protection Mechanism and expect offers to come in soon.
Kristalina Georgieva, the EU's crisis response commissioner, said that in an environmental catastrophe such as the Hungarian one, the effects do not stop at national borders and a European response is the most effective way of dealing with it.
"In this moment of need, I call all EU member states to respond with generosity to the request of Hungary," Georgieva stated.
Prime Minister Viktor Orbán visited the disaster area and admitted the catastrophe was "more than likely" caused by human failure.
"Two weeks ago there was some control procedure. The official report said that everything is OK and you can see how, what does it mean OK?" said Orbán, appearing on television with his boots covered in red mud.
Orbán also announced that some villagers would be evacuated and people would be moved to accommodation well away from the disaster area. He also said he had contacted wealthy Hungarians abroad to provide financial assistance.
More hazardous pools in Hungary
In the meantime, WWF International warned that Hungary has two other sludge ponds storing similarly toxic and highly alkaline red mud from bauxite processing. One is located at Almásfüzitő, on the river bank just 80km upstream from Budapest, and stores around 12 million tones of sludge in seven pools covering around 40 hectares (200 acres).
WWF Hungary's acting CEO Gábor Figeczky, who has visited the disaster area, slammed the Hungarian authorities for their handling of the situation.
"We still don't know what caused this accident and what was in the waste," said Figeczky. "And while we are assured that the dam has stopped leaking, authorities have closed the airspace over the site to all but official and company flights."
The EU's Mining Waste Directive, which was introduced following major toxic spills at Baia Mare in Romania in 2000 and Donana in southern Spain in 1998, was meant to prevent exactly this kind of disaster from happening again, WWF points out.
"Unfortunately, the EU Mining Waste Directive – which WWF was substantially involved in developing – was significantly weakened as the result of industry lobbying," said Andreas Beckmann, head of WWF's Danube-Carpathian programme.
Other Danube countries also pose threat
In Serbia, numerous heavy industrial facilities are located close to the river, including the Pancevo complex of oil refineries, fertiliser and vinyl chloride manufacturing plants and associated storage facilities.
Following NATO bombing in 1999, surveys on soil and water samples "showed the presence of notable quantities of mercury, polycyclic aromatic hydrocarbons (PAHs), ethylene dichloride (EDC), and other highly toxic substances, including dioxins," WWF recalls.
In 2006, a punctured fuel tank at the Serbian port city of Prahavo sent a slick 50-100m long and 300 metres wide as far down the river as Romania.
Close to 20 tailings dams, some of which have been decommissioned but still have heavy metals buried underground, litter Bulgaria.
Romania, the site of a massive cyanide-contaminated gold processing waste spill into Danube tributaries in 2000, is currently seeing protests over a government decision to approve a massive new mining project at Roşia Montană.
(With additional reporting from EurActiv Hungary.)