Ukrainian presidential advisor says the West is financing Russia's invasion with 'bloody money' from oil and natural gas purchases

• Western imports of Russian natural gas and oil give "bloody money" to Putin, a Zelensky advisor told CNBC.
• Oleg Ustenko said that the purchases were ultimately financing Russia's invasion of Ukraine.
• Russia is the world's third-biggest oil producer after the US and Saudi Arabia.

A top economic advisor to Ukrainian President Volodymyr Zelensky told CNBC that countries who were importing oil and natural gas from Russia were ultimately financing the country's invasion of Ukraine with "bloody money."

International governments have imposed massive sanctions on Russia, aimed at bringing the country's economy to its knees and cutting off funding for its military. Measures have included blocking transactions from Russia's central bank and barring some banks from using SWIFT for communications about cross-border transactions.

But the sanctions have avoided targeting Russia's oil and natural gas exports, which many countries, particularly in Europe, rely upon.

Oleg Ustenko, one of Zelensky's advisors, told CNBC on Monday that countries buying Russia's oil and natural gas were "responsible" for financing Russia's military actions.

"It's extremely important to cut off them from these bloody money receipts," Ustenko said. "And we do believe that by doing this we will be able really to hit Russians very hard." Zelensky urged countries to boycott imports of Russian oil and natural gas on Monday.

Russia has the world's largest reserves of natural gas. The European Union gets around 40% of its natural gas from Russia, and the country sold about $100 billion worth of oil and gas to Europe in 2021, according to estimates from William Jackson, an economist at Capital Economics.

Russia is also the world's third-biggest oil producer after the US and Saudi Arabia, accounting for about 12% of global oil production.

The West in particular has been hesitant to stop imports from Russia because they would need to find other sources and prices could soar. 

Secretary of State Antony Blinken told NBC Sunday that the US was in "very active discussions" with Europe about banning the import of Russian oil. His comments helped push oil prices up to the highest in almost 14 years.

Russian deputy prime minister Alexander Novak said on state television Monday that a ban on Russian oil would lead to "catastrophic consequences" for the global market and cause oil to surge to $300 per barrel "if not more."

He also warned that Russia could cut off gas pumping through the existing Nord Stream 1 gas pipeline which pumps Russian natural gas to Europe. Germany halted plans for the Nord Stream 2 pipeline after Russia sent troops into Ukraine.

Oil giant Shell apologized on Tuesday for purchasing a cargo of crude Russian oil, just days after the oil giant said it would limit business with the country. The company also announced plans to withdraw from the Russian oil and gas industry and shut down all of the company's service stations in the country.

At the time of the purchase, Shell said: "We will continue to choose alternatives to Russian oil wherever possible, but this cannot happen overnight because of how significant Russia is to global supply."