Budapest: Hungarian officials on Friday played down the threat of disastrous pollution to the Danube river from an industrial accident in Hungary, while its Prime Minister said the situation was under control.
The death toll from Monday`s disaster meanwhile rose to seven, officials said, and one person was still missing.
Prime Minister Viktor Orban, who declared a state of emergency in three counties earlier this week, insisted there remained little risk of the pollution running into the Danube, Europe`s second-longest river.
"The good news is that we have succeeded in bringing it under control and very probably waters threatening the environment will not enter the Danube, even on Hungarian territory," Orban said during a visit to neighbouring Bulgaria.
Environment state secretary Zoltan Illes also insisted the pollution "won`t reach the lower Danube."
He praised rescue teams -- who were for dropping acid and gypsum into the Danube and its tributaries from planes to neutralise the alkaline effects of the toxic sludge -- for "preventing the heavy metals and the alkaline from traveling further downriver."
Toxic sludge from an alumina processing plant in western Hungary burst out of a storage reservoir on Monday, pouring into villages and killing all life in at least one small river.
Dead fish were also seen floating in the Danube on Thursday, but environmental officials on Friday said that water quality samples were close to normal in the river.
On Friday afternoon, alkaline levels showed a reading of pH 8.3 at Komarom, around 80 kilometres (50 miles) west of Budapest, down from earlier in the day, according to a spokeswoman for the disaster relief services, Jyorjyi Tottos.
The level is only slightly higher than normal and is not harmful to the environment, Tottos said.
Water alkalinity is a measure of river contamination and on a scale of 1-14, pH values of 1-6 are acid, between 6 and 8 are neutral, and readings of 8-14 are alkaline.
Authorities said they expect the clean-up in two of the hardest-hit villages, Kolontar and Devecser, to be finished next week.
But environmental groups rang alarm bells about the longer-term consequences.
In Vienna, Greenpeace said it had found "surprisingly high levels" of arsenic and mercury in the caustic, foul-smelling red sludge that escaped from the reservoir in Ajka, 160 kilometres west of Budapest.