Oil prices have surged past $103 a barrel this morning amid growing fears that a war in Europe could disrupt global energy supplies.
Russian President Vladimir Putin launched a military operation in the eastern Donbas region of Ukraine overnight, sending Brent Crude to a seven-year high.
Russia is the second biggest exporter of crude oil after Saudi Arabia. It is also the world's largest natural gas exporter.
Sanctions
The US increased pressure on Russia on Wednesday by imposing penalties on the Russian firm behind the Nord Stream 2 gas pipeline and its corporate officers.
Nord Stream 2 is a 1,200km pipeline under the Baltic Sea, which is designed to take gas from the Russian coast near St Petersburg to Lubmin in Germany.
On Tuesday, Germany froze final approval for the pipeline, which has been built but is not in operation.
How high could oil prices go?
A leading economist has warned that oil prices could top $140 a barrel if the Russia-Ukraine crisis continues to escalate.
Edward Gardner, a commodities economist at Capital Economics, said yesterday that that Europe and Russia's mutual energy dependency could be "thrown out the window" in the event of further escalation.
"It is not in the economic interests of either Russia or the West to use trade in energy as a weapon against each other," he said.
"But that is not to say it won’t happen. If energy flows were disrupted, we think oil prices could settle at around $120-140 per barrel, before coming back down as trade flows re-route."