Photo from UNIAN Acting Head of the State Service of Geology and Mineral Resources Oleh Kyryliuk says the Russian Federation illegally seized two-thirds of the Ukrainian territory on the Black Sea shelf following the annexation of Crimea in the spring of 2014. "There were quite significant explored reserves on the Black Sea shelf before the annexation of Crimea. Estimated reserves ranged from 100 to 300 billion cubic meters of gas on a more than 130,000 sq km shelf within the Ukrainian territory. After the annexation of Crimea, the territory of our shelf was reduced by 66.7% and is now about 40,000 sq km. We are talking about the territory where research is currently being conducted and reserves have been established," Kyryliuk told a press conference. Read alsoRussia stealing Ukraine&#39;s gas: over 3.5 bcm illegally extracted from gas field in CrimeaHe noted that the approved gas reserves on the shelf areas that remained under Ukraine&#39;s control are at about 37 billion cubic meters. About 10 billion cubic meters are the reserves on the shelf of the Azov Sea. As was reported earlier, Russia seized drilling rigs and other assets of Ukraine&#39;s Chornomornaftogaz during the annexation of the Crimean peninsula in 2014. National Joint-Stock Company Naftogaz of Ukraine has lost control over the enterprise. Naftogaz said it would sue Russia over Crimean assets. In 2016, the court issued an arrest warrant in relation to drilling rigs of Chornomornaftogaz earlier seized by Russia.