ONGC Videsh Ltd (OVL), the overseas arm of state-owned Oil and Natural Gas Corporation (ONGC), holds 26 per cent stake in Suzunskoye, Tagulskoye and Lodochnoye fields -- collectively known as the Vankor cluster in the north-eastern part of the West Siberia. Indian Oil Corp (IOC), Oil India Ltd (OIL) and Bharat PetroResources Ltd (a unit of Bharat Petroleum Corp Ltd or BPCL) hold another 23.9 per cent. Russia's Rosneft is the operator with 50.1 per cent interest.