A court based in The Hague has ordered Russia to pay about $50 billion to a group of former shareholders of the Yukos oil company.
The Permanent Court of Arbitration ruled on July 28 that Russia violated the 1991 international Energy Charter when it dismantled Yukos and auctioned off its main assets in 2004.
The court said officials at state-owned Rosneft, which acquired most of Yukos's assets, were working for Russian President Vladimir Putin in destroying Yukos.
The plaintiffs, Group Menatep Limited (GML), had sought damages of $114 billion. The court also ordered Russia to pay $65 million to compensate GML's legal costs. It was one of the largest awards the court has ever made.
Yukos was formerly owned by Mikhail Khodorkovsky, who served eight years in prison on tax-evasion and embezzlement charges before being pardoned last year.
In 2005, Khodorkovsky sold his interest in Yukos to GML, which is owned by former Yukos official Leonid Nevzlin and other top Yukos officials. Khodorkovsky is not a party to the present ruling.
After the ruling, Rosneft issued a statement saying that all deals it was involved in were made in compliance with Russian law.
It assured shareholders it is not a party to the case decided in The Hague and does not anticipate any impact on its activities or assets.
Speaking in Moscow on July 28, Russian Foreign Minister Sergei Lavrov said Moscow will use every legal avenue to contest the ruling.
Russia's Finance Ministry later issued a statement officially announcing Russia would appeal the Hague court's decision.
The ministry said there were "serious flaws in the decision of the arbitration court" and called the court's ruling "politicized."
The Finance Ministry also claimed the Hague court's decision runs counters to conclusions of the European Court of Human Rights, "which twice ruled that Yukos had committed massive tax evasion."
Russia has 10 days to appeal the ruling.
In a separate case, the European Court of Human Rights in Strasbourg is expected to announce on July 31 a decision on another multibillion-dollar suit by Yukos shareholders against Russia.