According to the website, Rosneft will buy 5.14 million tonnes of oil worth 132.5 billion roubles ($1.9 billion) from Gazprom Neft.

The price works out at around $46 per barrel compared to a current price of Russian Urals crude blend of $51 per barrel.

Rosneft's total oil production is seen at 241 million tonnes of oil (4.82 million barrels per day) next year.

Rosneft has not disclosed its oil purchases for the whole 2018.

Rosneft said, in an emailed response to a request for a comment, that the purchases will allow it to cut transportation costs and are "usual practice in the oil industry".

(Reporting by Rinat Sagdiev and Olesya Astakhova; writing by Vladimir Soldatkin; Editing by Elaine Hardcastle)