U.S. inflation accelerated last month as gas prices spiked after renewed fighting in the Middle East.

The consumer price index rose 3.4% compared with a year ago, the Labor Department said Friday.

That was the same as July.

But prices jumped 0.4% from July, four times the 0.1% increase the month before.

The report increases pressure on the Federal Reserve to raise its benchmark interest rate next week.

That could lift mortgage and auto loan costs in the months ahead.

Fed Chair Kevin Warsh and other officials have said they need to see continuing disinflation to leave rates where they are.

Kathy Bostjancic, chief economist at Nationwide, said the August report did not deliver that.

Gas prices rose 3.9% from July to August and are more than 27% higher than a year earlier.

Diesel prices have hit record highs above $6 a gallon, pushing up shipping costs for groceries and other goods.

Airline tickets rose 2.7% for the month and have soared more than 23% from a year earlier.

Hotel room prices climbed 2.4% from July to August.

Core prices exclude volatile food and energy.

They were 2.4% higher than a year ago, down slightly from July's 2.5%.

But monthly core prices rose 0.3%, the largest increase since April.

Wall Street investors now see a more than 80% chance the Fed will raise rates Sept. 16, according to CME Fedwatch.