Workers remove contaminated fish from the area

As the Spanish Government announced an enquiry into the disaster, environmentalists accused it of failing to ensure the security of the dam wall which collapsed, releasing the chemical spill.

The government claimed success in keeping the poisonous spill away from the Do�ona National Park by constructing artificial earth banks to contain the flood.

But there are still fears that the park, Europe's largest nature reserve, has become contaminated as chemicals have seeped into the groundwater.

Humans could be affected

Shellfish and other wildlife have been badly hit by the pollution

A tide of poisoned water and mud continues to devastate surrounding areas. Birds, fish and shellfish are affected and toxic chemicals will remain in the food chain for decades.

There are fears that the poisons could eventually spread to humans. Workers were clearing dead fish from the mud on Tuesday in an attempt to reduce the amount of poison entering the food chain.

Thousands of farmers have seen their crops ruined and their land rendered infertile, possibly for a whole generation. The mayors of seven towns along the river have warned citizens not to drink from ground wells.

'Catastrophic' - environment minister

The dam was hastily constructed to contain the toxic waste

Spanish Environment Minister Isabel Tocino described the ecological damage to the region as "catastrophic". Government officials have announced the launch of an investigation into the disaster.

Attorney General Jesus Cardenal vowed to use "all legal means" to find out what led to Saturday's collapse of the dam wall which had been hastily constructed to hold back toxic waste at the Los Frailes iron pyrite mine.

Environmentalists have blamed the catastrophe on the Canadian-Swedish company Boliden Ltd, which owns the Los Frailes mine where the spill took place - and on the government for failing to enforce security provisions.

"The company and the authorities knew there were concerns about the security of the dam," Spanish Greenpeace representative Juan Lopez said.

Eva Hernandez, also of Greenpeace, described how herons and storks were feasting on hundreds of fish writhing in black sludge.

"One way or another, they will all be contaminated by highly-toxic products absorbed by the fish," she said.

The situation is especially serious as many of the birds are currently raising chicks, and the poisoning of fish stocks will remove a vital source of food.