Union Petroleum and Natural Gas Minister Dharmendra Pradhan on Sunday said the Russian oil major Rosneft plans to tap the retail fuel market in India in a big way."The Russian oil major who took over Essar Oil recently is planning in a big way to make inroads into India's retail fuel market," Pradhan told reporters after attending the City Gas Distribution (CGD) project to supply piped natural gas (PNG) to households in Bengaluru.To a query on the size of investment to be made by Rosneft and Essar, he said both the companies have invested $13 billion in Indian market in the last financial year."It was one of the biggest deals in the oil industry in the world," he said.During the second quarter of this financial year, BP and Reliance Industries have announced a $6 billion investment in India and Pradhan said this "indicates the progressive and reformative nature" of the Narendra Modi government.