KIEV, May 15 - Ukraine asked Gazprom of Russia to return 2 billion cubic meters of natural gas seized after the occupation and annexation of Crimea, deputy energy and coal industry minister Ihor Didenko said Thursday.

The gas was kept in underground gas storage facilities in Crimea before the Ukrainian Black Sea peninsula had been annexed by Russia in March. The gas was owned by national energy company Naftogaz Ukrayiny via its 100% subsidiary Chornomornaftogaz.