Gazprom Neft, the oil arm of Russia's state-controlled natural gas monopoly Gazprom, said on October 28 that it has challenged European Union sanctions against the firm in the EU's Court of Justice.
The sanctions against Gazprom Neft were imposed as part of wider restrictions against Russia over its illegal annexation of Crimea from Ukraine and its support for pro-Russian separatists in eastern Ukraine.
The EU sanctions restrict the ability of Gazprom Neft, Russia's fourth biggest oil producer by output, to raise funds on European markets.
The United States also has imposed sanctions against Gazprom Neft in response to Russia's role in Ukraine's crisis.
The West says Moscow is supplying arms and troops to help pro-Russian separatists in eastern Ukraine battle Ukrainian government forces.
Moscow denies that, despite increasing evidence to support the charges.
Based on reporting by Reuters, AP, and TASS