Eyewitness

Students in southern Brazil are helping 2,200 workers, police and military forces to combat an oil spill described as the country's worst environmental disaster for 25 years.

An estimated 25,143 barrels of toxic Colombian crude poured into the Iguacu river from a burst pipeline at the Getulio Vargas refinery of the state oil company, Petrobras.

Heavy rains spread the toxic effects of the hydrocarbons to the drinking water of riverside villages, and it is feared that more rain could push the slick 600km farther downstream to the panoramic Iguacu falls on the border with Argentina and Paraguay. The Argentine government has requested urgent United Nations intervention and, with Paraguay, is considering suing the Brazilian government.

A preliminary report by a commission including experts from the Paran National University attributed the accident to human error and technical problems.

Oswaldo Sev Filho, an industrial petroleum specialist at the state university of Campinas near Sio Paolo, said Petrobras lacks the expertise to deal with spills. Professor Filho, co-author of a recent book on industrial accidents, said: "The real problem is that our major petroleum company, which has ten more refineries throughout the country, is unable to cope with oil spills.

"We know how regularly Petrobras carries out inspections, and we also know that rather than halt production for a day to replace a worn duct, it will tend simply to reduce pressure and continue using the old one.

"Fire is one of the main dangers. Oil that has not been completely removed from the river or the ground will evaporate, producing an invisible but highly inflammable cloud of volatile hydrocarbon. A carelessly discarded cigar where there is a dense concentration of the substance could result in another disaster."

Petrobras consultants said that more than half the spill had been recovered while 20-30 per cent more had evaporated. They ruled out the oil's reaching the falls.

The company faces a fine of $83 million for negligence, on top of three fines totalling $81 million already this year.