Trading sources told Reuters on Monday Rosneft issued its regular six-month crude tender offering a maximum of 10.6 million tonnes of oil, down 4.8 million from the previous tender.

The decline in tender volumes follows an agreement by Rosneft 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.

In the current tender for April-September, Rosneft is offering to sell 0.6-2.0 million tonnes from the port of Ust-Luga and 1.8-5.0 million tonnes from Primorsk, both in the Baltic.

From the Mediterranean port of Novorossiisk, it is offering 0.96-1.92 million tonnes in 80,000-tonne tankers and 0.84-1.68 million tonnes in 140,000-tonne tankers.

During the previous tender for October-March, Rosneft offered 0.6-3.0 million tonnes from Ust-Luga and 2-7 million tonnes from Primorsk. From Novorossiisk it offered 0.96-2.88 million tonnes in 80,000-tonne cargoes and 0.84-2.52 million tonnes in 140,000-tonne cargoes.

The previous tender was won by Glencore, Vitol and Shell. Glencore won all volumes from Ust-Luga, while Vitol won cargoes from Novorossiisk on the Black Sea. Shell, Vitol and Glencore split volumes from Primorsk, Russia's largest Black Sea port.

Since then, Glencore and Vitol have agreed to lend money to Rosneft under a five-year supply deal and deliveries are expected to begin in the second quarter, which means volumes through the six-month tender will have to be reduced.