Former majority owners of Yukos Oil Co. won a landmark $50 billion award against Russia for the confiscation of what was once the nation’s largest oil company after a decade-long battle.

The Permanent Court of Arbitration in The Hague ruled that Russia is liable to pay almost half of the $103 billion plus interest they sought, GML Ltd., the holding company for Yukos’s former main shareholders, said today. The decision showed Russia’s campaign against Yukos was “politically motivated,” GML head Tim Osborne said in London.

The decision against Russia marks a fresh headache for President Vladimir Putin, who faces intensifying U.S. and European sanctions aimed at forcing him to end the conflict in neighboring Ukraine. Collecting may take years of wrangling, according to former Yukos legal counselor Dmitry Gololobov.

“A superpower like Russia has been unanimously held accountable for its violation of international law by an independent arbitration tribunal of the highest possible repute,” Emmanuel Gaillard, one of GML’s lawyers, said in London. “Today is a great day for the rule of law.

Russia must pay the award by mid-January or face penalties, according to GML. The possibility for appeal is limited to ‘‘technical’’ grounds within the Dutch courts, Gaillard said.

Khodorkovsky, Yukos

The decision risks dragging Russia’s two biggest companies, oil producer OAO Rosneft and natural gas exporter OAO Gazprom, into extended legal battles. The state-controlled companies’ assets may be targeted because they were beneficiaries of expropriated Yukos assets, said another GML lawyer, Yas Banifatemi. Rosneft and Gazprom both declined about 2 percent in Moscow trading.

Putin’s government dismantled Yukos in 2004 to 2007 over $27 billion in tax charges after imprisoning Chief Executive Officer Mikhail Khodorkovsky. The former owner, who isn’t party to the award, said in a statement today that it was ‘‘fantastic that the company shareholders are being given a chance to recover their damages.”

Most of its former assets were acquired in a series of forced sales by Rosneft, which has since become the world’s largest publicly traded oil company by output. Gazprom bought stakes in Yukos natural gas assets from Eni SpA and Enel SpA, which won them at auction in 2007.

Rosneft Assets

Rosneft complied with the law regarding Yukos assets and doesn’t expect the decision to “negatively affect its commercial activity or assets,” the oil producer said in a website statement. Gazprom declined to comment.

The Yukos shareholders have the right to go after state assets if Russia doesn’t pay, Osborne said. “I don’t think that Rosneft can be 100 percent confident that all their assets in the West will be secure,” he said in an interview with Bloomberg Television.

Russia will have an opportunity to appeal, Foreign Minister Sergei Lavrov said today at a televised briefing. “Russia will use all available legal means to defend its position,” he said.

Russia will probably refuse to pay the damages, and seizing state assets abroad will be a difficult task, according to Gololobov.

“Russia has the money to hire the best international lawyers, who won’t give up without a fight,” Gololobov said by e-mail before the ruling was announced. “So the Yukos affair could easily go on for another 10 years.”

Politically Motivated

Khodorkovsky, once Russia’s richest man with a fortune of $15 billion, was freed in December under a presidential pardon after serving a decade in prison camps. He has called the charges against him revenge for his financing of opposition parties. The Kremlin denies the claim, saying it was purely a matter for the courts.

The ruling found that “that the primary objective of the Russian Federation was not to collect taxes but to bankrupt Yukos and appropriate its underlying assets for the benefit of the state in the guise of Rosneft,” Osborne said.

Khodorkovsky, who’s living in Switzerland, said he isn’t entitled to any part of the damages because he transferred his Yukos stake to fellow shareholder Leonid Nevzlin to protect the company when he became a target of the Russian courts.

Nevzlin is beneficial owner of slightly more than 70 percent of GML, while four other partners -- Platon Lebedev, Mikhail Brudno, Vladimir Dubov and Vasily Shakhnovsky -- each have a little less than 7.5 percent. GML used to own 60 percent of Yukos.

100 Countries

GML initiated its case in 2005 under the Energy Charter Treaty, an international agreement that in part regulates investments in the energy industry. Russia signed but never ratified the treaty. The Hague tribunal ruled in 2009 that it would hear the case.

The Yukos plaintiffs will have the right to go to arbitration courts in about 100 countries that are party to the 1958 New York Convention to enforce the ruling, according to Gus Van Harten, a professor specializing in arbitration at York University’s Osgoode Hall Law School in Canada.

Because it will be hard to seize Russian government assets, which are mostly protected by diplomatic immunity, state companies such as Rosneft and Gazprom would be an easier target, he said.

Claudia Annacker, a partner with U.S. law firm Cleary Gottlieb Steen & Hamilton who has been representing Russia in the Yukos lawsuit, didn’t immediately respond to an e-mailed request for comment.

Putin Opponents

Putin is confronting mounting international pressure after the downing of a Malaysian passenger jet in eastern Ukraine that killed 298 passengers and crew. The Obama administration has accused pro-Moscow rebels of shooting the plane down with a Russian-supplied launcher. They deny involvement, and Russia is pointing the finger at Ukraine.

Putin has said his opponents are using the crash for “selfish political gains.” The EU last week warned that it may restrict the country’s access to capital markets and sensitive energy and defense technologies. The bloc is considering banning European purchases of bonds or shares sold by Russia’s state- owned banks, according to a proposal presented to the 28 member states.

The European Court of Human Rights will decide this week on a $38 billion claim for “just satisfaction” filed by ex-Yukos management that would benefit all former shareholders, Claire Davidson, a spokeswoman for the former managers, said by phone today.