Major oil companies with interests in Russia responded to new U.S. sanctions against Russia, as the against seven Russian government officials and 17 companies linked to President Vladimir Putin in its latest action to punish Moscow for its intervention in Ukraine.
Brent crude rebounded back above $109 a barrel on Tuesday on Ukraine worries, after making its biggest daily fall in a month on Monday on words of recovering supplies out of Libya.
Italian oil and gas giant Eni weighed in on Tuesday, saying it was experiencing "business as usual" with its main gas supplier, Russia's Gazprom. Eni's midstream boss Marco Alvera said ties with Gazprom, which is Italy's biggest gas supplier, have not been adversely affected by Russia's increasing isolation in the face of western sanctions.
Russian oil giant Rosneft saw its shares drop Monday after its chief executive, Igor Sechin, was among those singled out by the United States for punitive sanctions. Rosneft was the only publicly traded Russian company to be affected by the sanctions. Its shares lost about 2 percent even as Moscow's MICEX index rose Monday.
Standard and Poor's ratings agency cut the credit ratings of state-controlled Rosneft and Gazprom to BBB- from BBB on Monday, the agency said in a statement on its website.
The downgrade, to a notch above junk rating, came after the agency cut Russia's sovereign rating on Friday, also to BBB-, the lowest investment grade category.
Anglo-Dutch oil major Shell said it will comply with all international sanctions, following the sanctions against Rosneft's Sechin.
"Shell monitors trade controls and sanctions closely and will respond appropriately to ensure that we comply with all applicable international sanctions and related measures," a spokesman said.
British oil major BP said it intends to remain a long-term investor in Rosneft following the U.S. decision to hit Russia with sanctions.
"We are committed to our investment in Rosneft, and we intend to remain a successful, long-term investor in Russia," a BP spokesman said.
He added the company, which holds a 19.75 percent stake in Rosneft, is now considering what the U.S. sanctions announcement means for BP's business.
The U.S. sanctions on Monday were followed closely by new penalties from the European Union.
A senior Russian diplomat sharply criticized the new round of sanctions, saying the measures were illegitimate and uncivilized and that restrictions on high-tech exports from the United States marked a return to Cold War practices.
"We decisively condemn the series of measures that has been announced in an attempt to put sanctions pressure on Moscow," Deputy Foreign Minister Sergei Ryabkov said in comments posted on the ministry's website.
For their part, senior U.S. Republican lawmakers said on Monday the latest sanctions are too mild to deter Moscow from further action in Ukraine, keeping up pressure on the Obama administration to take stronger action.
Tennessee Senator Bob Corker, the top Republican on the Senate Foreign Relations Committee, called the new sanctions "just a slap on the wrist."
—By Reuters. CNBC staff contributed to this report.