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.

An armed man in military fatigues stands guard outside a regional administration building seized by pro-Russian separatists in the eastern Ukrainian city of Slavyansk on April 27, 2014.

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.



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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.