The price of oil has jumped to $105 a barrel amid signs the conflict in the Middle East will not be resolved quickly, fuelling fears that inflation could accelerate.
With the conflict between the US and Iran in the Gulf intensifying in recent days, the cost of both crude oil and gas has been rising sharply. Brent crude went back above $100 a barrel on Wednesday and has continued to climb.
The war has led to the effective closure of the Strait of Hormuz, preventing supplies of oil and gas from the Gulf from reaching global markets.
Worries over higher inflation have in turn helped to push bond yields in the UK to their highest level in decades.
Speaking at a Republican Party convention in Texas on Wednesday, President Trump said he did not think the fighting would end until after the US mid-term elections in November.