(This content was produced in Russia where the law restricts coverage of Russian military operations in Ukraine)

MOSCOW, Dec 27 (Reuters) - Russia will be forced to reduce its oil production due to Western sanctions, while mature fields, which do not enjoy tax breaks, will likely bear the brunt of the contraction to cushion producers' losses, analysts said on Tuesday.

Russia may cut oil output by 5%-7% in early 2023, as it responds to Western price caps on its crude and refined products, and halt sales to the countries that support them, Deputy Prime Minister Alexander Novak said on Friday.

Russia, which produces 10% of the world's total oil output, has granted tax breaks to new fields to support production and generate revenue for the state budget.

The sanctions over Ukraine have hit sales of Russian oil, which jointly with other key Russian commodity, natural gas, account for around 45% of state budget revenues. Exports of Russia's flagship Urals crude blend from the Baltic Sea ports may fall by up to a fifth in December.

Russia has voluntarily cut oil production in the past, such as in spring of 2020, when output was cut by almost 20% to 8.5 million barrels per day as part of the OPEC+ group's response to the COVID-19 pandemic.

"The companies will cut production at fields with the full (rate) of MET (mineral extraction tax), just as they did as part of the OPEC+ cuts", said Kirill Melnikov, analyst at the Centre for Energy Development.

Russian oil majors did not respond to requests for comment.

Oil and gas condensate production at Russia is expected to rise this year to 535 million tonnes (10.7 million barrels per day) from 524 million tonnes in 2021. It is may fall to 490 million tonnes next year.

Marcel Salikhov, head of the Moscow-based Institute for Energy and Finance, said that companies will continue developing high-earning projects under the profit-based tax scheme rather than the MET.

Alexei Kokin, an analyst at the Otkritie brokerage, thinks that oil producers will not cut output of the Asia-bound ESPO blend.

"I think profitability of exports via the East Siberia - Pacific Ocean (ESPO) pipeline is higher than via the European ports, as ESPO is $30 per barrel more expensive than the Urals blend," he said. (Reporting by Olesya Astakhova; writing by Vladimir Soldatkin; Editing by Louise Heavens)