Hungarian authorities evacuated the village of Kolontar at dawn Saturday, fearing a new toxic flood from a storage reservoir at an aluminium processing plant after one that killed seven people.
"The evacuation of Kolontar began at six in the morning (0400 GMT) after we noticed that the dam started weakening at tank number 10," Disaster Relief Team chief Tibor Dobson told AFP.
About 800 villagers were transported by bus to Ajka, the nearest major city which is 160 kilometres (100 miles) from the capital Budapest.
Kolontar is a stone\'s throw from the reservoir that burst on Monday, spilling 1.1 million cubic metres (38.8 million cubic feet) of foul-smelling red toxic sludge into villages and rivers in the country\'s worst ecological disaster.
"People may return once the dam has been strengthened," said Dobson.
Police and army personnel had also deployed into the neighbouring village of Devecser to urge people to pack all they need in one suitcase so they could leave quickly if necessary, the official said.
"If deemed necessary, the nearby Devecser may also need to be evacuated," Dobson said.
Authorities started to build a dam in Kolontar to save those houses that were undamaged, the Hungarian News Agency MTI reported. The new dam would be four to five metres (around 13 to 16 feet) high and made of earth and rocks.
"The evacuation was decided by Interior Minister Sandor Pinter, who attended a local committee meeting early Saturday morning," said Dobson.
Top officials including Prime Minister Viktor Orban, Defence Minister Csaba Hende, national police chief Jozsef Hatala and the national chief of disaster relief services Gyorgy Bakondi were all at the scene.
The death toll rose to seven on Friday after another body was found. One person is still missing. Around 150 people have been wounded, many suffering burns.
Kolontar was devastated in the flood, with cars overturned and swept away, houses swamped, broken furniture and debris strewn everywhere.
Officials have insisted there was little risk of the pollution running into the Danube, Europe\'s second-longest river.
Dead fish were seen floating in the Danube on Thursday although environmental officials that water quality samples were close to normal in the river.