Earlier reports mentioned 100-300 tons of spilled fuel oil.
On June 15, in the evening, 26 tank-cars loaded with fuel oil came off the railroad tracks. The major problem was that the incident occurred 150 meters from the bank of the Vazuza River, the tributary of the Volga River, which is the main waterway in the European part of Russia flowing into the Caspian Sea.
At present, the situation in the Tver region (200 kilometers to the northwest of Moscow) has been contained, Vorobyov reported.
"The situation in the Tver region is developing quite well despite the fact that the accident was very serious. Only four out of 26 tank-cars did not leak," he said.
According to Vorobyov, the riverbed of the Gostizha River, which flows into the Vazuza River, has been completely cleaned.
The Vazuza River is supposed to be cleaned from the fuel oil spill today, the first deputy minister said. "After that we will start cleaning the Volga river," he added.
The incident does not pose a threat to ecology, Vorobyov said. According to his data, at a 2.5-kilometer stretch near the confluence of the Vazuza and Volga, the hazard concentration limit in terms of the presence of oil components does not exceed 0.5.
"Even at this mostly polluted stretch there is no threat to human ecology," Vorobyov said.
He added that there was no danger for water supply of Moscow, either. Earlier, there was a possibility of contamination of the Volga River, which serves as a source of water supply for Moscow.
"However, the local residents are facing a major problem because the area where they live has been seriously polluted," the first deputy minister said.
He promised that the emergency works will continue until the water-beds and the banks of all adjacent rivers in the area have been completely decontaminated.
"After removing the tank-cars, we will clean the surrounding territory, as well," he added.
Vorobyov also said that the Emergencies Ministry applied for the first time new technologies using helicopters spraying the riverbanks with special reagents to liquidate the consequences of the fuel oil spill.
"These technologies are harmless for the environment and people. The decontamination will continue with the use of river boats spreading reagents on the riverbanks," he added.
