WASHINGTON, Jan 11 (Reuters) - Russia's oil revenues are decreasing because of the price cap put on crude by Western countries, a senior U.S. Treasury official told reporters on Wednesday.

The Group of Seven countries including the United States, Australia and the European Union are set to extend sanctions on Russia by putting a price cap on its oil products, such as gasoline and diesel on Feb. 5, after putting such a limit on Russian crude oil sales last year.

Europe can withstand pressures on oil products this winter brought about by Russia's invasion of Ukraine, because it has built of supplies of diesel and because of a warmer temperatures than expected, the Treasury official said. Some cheaper Russian diesel could end up being sold to countries in Africa and other places that have suffered high oil prices in the last year due to the conflict in Ukraine, the official said. (Reporting by Timothy Gardner; Editing by David Gregorio)