<div>Oil and Natural Gas Corp (ONGC) has paid just over $1.25 billion for a 15 per cent stake in Russian oil major Rosneft's Vankor oil field, a source with direct knowledge of the deal said on Friday.</div><div> </div><div>ONGC expects to get more than 3 million tonnes of oil a year (between 66,000 and 70,000 barrels per day) from its holding in the huge Siberian oil field, the source told Reuters on condition of anonymity.</div><div> </div><div>Rosneft earlier announced the deal to sell the interest in Vankor, a key source of supply to markets in the Asia-Pacific. Chief executive Igor Sechin said that talks with China's CNPC on a Vankor stake were continuing.</div>