The leak occurred on July 29 on the Druzhba pipeline in Bryansk region but became public only today.
The Ministry of Natural Resources initially said the leak has affected an area of around 10 square kilometers and had contaminated soil and water resources.
However, officials from the company that operates the pipeline, Transneft, and from the Emergency Situations Ministry later said the spill had affected an area of no more than 360 square meters and that clean-up operations were almost complete.
Transneft said the pipeline stopped pumping oil over the weekend, but that the flow had resumed today.
The pipeline carries oil to Germany, Poland, and Hungary, among other countries.
(compiled from agency reports)