Russian oil giant Public Joint Stock Company Rosneft Oil Company (MISX:ROSN) is in early talks with Reliance Industries Limited (NSEI:RELIANCE) for sale of its 49.13% stake in Nayara Energy Limited, which operates a 20-million tonnes-a-year oil refinery and 6,750 petrol pumps in India, sources said. Reliance has held preliminary talks for acquisition of Nayara, which will help it overtake state-owned Indian Oil Corporation (IOC) to become India's No.1 oil refiner as well as give a meaningful presence in the fuel marketing space. But the talks are at preliminary stage and there is no guarantee that they may lead to a definite deal as valuation remains a sticky ground, three sources with direct knowledge of the matter said.