Inflation in the U.K. held steady at 3.8% in the year to August, official figures showed Wednesday, a day before the Bank of England is widely expected to keep interest rates on hold.

The Office for National Statistics found food and drink prices rose for the fifth month in a row, but airfares fell sharply after a big spike in July.

Though inflation remains nearly double the Bank of England's target rate of 2%, most economists had anticipated a modest increase in August.

Stubbornly high inflation has been one of the reasons why the Labour...