Russian oil output could fall by 500,000 to 1 million barrels per day (bpd) early in 2023 after the European Union imposes a ban on seaborne imports from Monday, two sources at major Russian producers said.

The estimate is at the lower end of market analysts’ forecasts of the combined impact of the ban and a proposed price cap on Russian oil, although the sources said the true level would depend on several factors yet to be settled.

They requested anonymity to discuss sensitive market dynamics connected with the conflict in Ukraine that Russia calls a “special military operation”.

Alexei Kokin of Otkritie brokerage broadly agreed with their assessment of the likely impact of Western measures on Russian output.

“It’s roughly the same as the volume of seaborne supplies to the EU in recent weeks,” he said. “I don’t think they (Russian producers) will be able to divert that elsewhere.”

The West wants to squeeze Russia’s finances to reduce its ability to fund the conflict.

Exports of crude, gas and oil products account for the majority of Russia’s revenues, which have stayed high as disruption to production and sales following Western sanctions has been more than offset by high prices on international markets.

Russia’s budget revenues from oil and gas jumped by over a third in the first 10 months of the year.

Before the Ukraine conflict began on Feb. 24, Russia exported around 8 million bpd of oil and oil products.

The EU, its biggest buyer, cut purchases in response to the conflict, but Moscow successfully diverted supply to Asia and exports slipped only slightly to 7.6 million bpd.

Looking ahead to 2023, one of the main variables will be the ceiling G7 countries and the EU agree on importing Russian oil.