Oil prices have surged past $100 (£74) a barrel after Russian President Vladimir Putin launched a "special military operation" in the eastern Donbas region of Ukraine.
These are the highest levels seen by the international benchmark Brent crude futures in more than seven years.
Prices jumped earlier this week before cooling amid economic sanctions and moves to block a Russian gas pipeline.
Russia is the second biggest exporter of crude oil after Saudi Arabia.
It is also the world's largest natural gas exporter.
"We could see prices keeping the momentum," said Tina Teng, a markets analyst at CMC Markets.