The European Union is to send a task force to help tackle the cyanide spill that has killed fish and birds in tributaries of the River Danube.

The EU environment commissioner, Margot Wallstrom, said international experts would be sent to the area to find out what happened and how such a catastrophe could be prevented in future.

"We need an international task force to be formed to evaluate the damage and diminish the effects," she said.

On 30 January, 100,000 cubic metres of contaminated water burst through a dam at a gold mining works in northern Romania. It has since travelled 1000km through Hungary and Yugoslavia, where it has now entered the Danube.

The spill killed off wildlife in the affected rivers, and poisoned drinking water supplies. The cost of the clean-up and possible compensation could run into hundreds of thousands of dollars.

Polluter pays

Ms Wallstrom is the first high-ranking EU official to tour the scene of what has been called the worst ecological disaster to hit Europe since the Chernobyl disaster in 1986.

Although the EU would not get involved in efforts by Hungary, Romania and other countries to obtain compensation, Ms Wallstroem said it would be supportive.

"Whoever is responsible for the pollution should pay - that is our starting point."

She added that the EU could send experts to help Hungary and Romania, and might help fund the clean-up effort.

EU to help

The commissioner criticised the Australian firm Esmeralda Exploration - which co-owns the mine with the Romanian Government - for trying to down play the effects of the spill.

"They have to be prudent in what they are saying. This is a serious environmental accident. For the people who depend on this water, it is a catastrophe," she said.

Officials at the mining company have said they would fight any compensation claims.

Esmeralda chairman Brett Montgomery said on Thursday: "Quite clearly there has been contamination of parts of the river system in the region, and my heart goes out to those who may be suffering."

"I stress, however, that there is no evidence to confirm that the contamination and the damage said to have been caused is as a result of the tailings dam overflow."

'Bleach to blame'

The company's scepticism was backed by the director of the Romanian water commission, Petre Marinescu, who said it was bleach that had contaminated the rivers.

Some authorities in the region had used bleach to neutralise the initial cyanide spill, he said.

"They poured a certain amount of sodium hypochlorite into the Lapus river, to neutralise the cyanide.

"Now this substance contains also unbound chlorine, and it was the latter, probably, that made the fish dizzy and look as if they had been poisoned."