Global oil prices jumped after Israel said it had struck Iran in a dramatic escalation of tensions in the Middle East.
The price of the benchmark Brent crude rose more than 10%, reaching its highest level since January, before losing some gains.
Traders were concerned that a conflict between Iran and Israel could disrupt supplies coming from the energy-rich region.
The cost of crude oil affects everything from how much it costs to fill up your car to the price of food at the supermarket.