Around 540 cubic meters of fuel oil leaked from a 2,000 cubic meter container at the Energia rocket and space corporation in Korolyov, near Moscow, late on January 5. Some 300 cubic meters of the fuel polluted the Klyazma's tributary.
"The situation is grave and is getting worse by the hour," Yelena Zubakina said. "Our experts have found around 70 dead wild ducks in the Dulev brook, and only five birds have been taken to a specialist clinic in a serious condition."
Rescuers have already collected 95.8 metric tons of fuel oil from the spill site. A total of 231 people and 51 vehicles are involved in the cleanup operation.
The latest reports said the concentration of fuel oil in the Dulev brook has started to decrease.
However, World Wildlife Fund (WWF) Russia said in a report referring to a witness from the town that the 3 km long brook is polluted all over, and that fuel oil has formed a 40-50 cm thick layer on the surface, hampering the rescue effort.
WWF also said on Friday it had launched its own rescue operation.
