The Russian state budget could lose more than 460 billion roubles (5 billion pounds) over 10 years if the additional tax breaks for the oilfield in West Siberia are approved, the spokeswoman said.

"FinMin sees the introduction of (new) benefits as inexpedient as the company already receives some tax benefits on the mineral extraction tax for oil production at Priobskoye," she said.

Production at Priobskoye stands at around 500,000 barrels per day.

The RBC daily newspaper reported on Friday that Rosneft CEO Igor Sechin, Russia's most powerful energy executive, has asked President Vladimir Putin for additional tax relief for Priobskoye, saying the oilfield was too depleted.

Rosneft declined to comment.

In 2017, Rosneft managed to secure tax benefits for its Samotlor oilfield, also in West Siberia, worth 350 billion roubles over 10 years.

(Reporting by Darya Korsunskaya and Vladimir Soldatkin; editing by Jason Neely)