Former Ukrainian Prime Minister Yulia Tymoshenko's political party called for ending a deal that gave Russia rights to extend its military presence in the Crimea through 2042, Russia's state-run news agency RIA Novosti reports.
Russian energy company Gazprom cut natural gas supplies to Ukraine briefly in 2009 before Tymoshenko, when serving as prime minister, helped clinch a deal to resume supplies. The deal put tight restrictions on Kiev and Ukrainian President Viktor Yanukovych later landed new arrangements in exchange for an extended lease for the Russian Black Sea fleet in Crimea.
"The Ukrainian Constitution was violated," Tymoshenko's All-Ukrainian Union Fatherland party was quoted as saying. "It clearly states (that) foreign military bases on Ukrainian territory shall not be permitted."
Tymoshenko is serving a seven-year prison sentence after being convicted on charges she abused her authority in the gas deal with Gazprom. She was the president of United Energy Systems of Ukraine, a primary importer of Russian natural gas, in the 1990s.