Russia`s Rosneft plans to cut volumes of crude it sells through its biggest six-month tender by almost a third, traders said on Monday, as the state oil major prepares to clinch an oil-for-loans deal with traders Glencore and Vitol. Trading sources told Reuters on Monday Rosneft issued its regular six-month crude sell tender offering a maximum of 10.6 million tonnes of oil, down 4.8 million from the previous tender. Rosneft is seeking to borrow up to $10 billion from Glencore and Vitol, using future oil exports as collateral, to complete its purchase of TNK-BP and become the world`s biggest listed oil producer.