Lower oil prices and Western financial sanctions imposed over the Ukraine crisis will cost Russia around $130-140 billion a year - equivalent to around 7 percent of its economy - Finance Minister Anton Siluanov said on Monday.

His comments are the latest acknowledgement by Russian policymakers that sanctions restricting borrowing abroad by major Russian companies are imposing heavy economic costs. But in Siluanov's view, the fall in oil prices is the bigger worry.

"We're losing around $40 billion a year because of geopolitical sanctions, and about $90 billion to $100 billion from oil prices falling by 30 percent," he told a news conference.