CPI inflation leapt to an annual rate of 5.2% in September, up from 4.5% in August. Energy price increases were the main culprits, according to the Office for National Statistics: average gas and electricity bills went up by 13% and 7.5% respectively in the month, and are up 18% compared with a year ago.

The retail prices index (RPI), which includes housing costs, rose to 5.6% in September from 5.2% in the previous month.

CPI inflation now stands at its highest since official records began in January 1997.

The increase in inflation came as no surprise to the Bank of England and to some forecasters, who have been predicting that prices would rise before falling back next year.

The Bank’s Monetary Policy Committee is not expected to increase interest rates from the record low of 0.5%, despite the price rises.

“The Bank is clearly more concerned about the current fragility of the recovery than current above-target inflation, meaning further stimulus could well be on the cards as policymakers seek to prevent the country from sliding back into recession if business and consumer confidence fails to pick up soon, which seems unlikely,” said Chris Williamson, economist at financial information company Markit.

Today's CPI figure will be used to calculate next April's increase in the state pension, and jobseeker’s allowance, while the RPI rise will be the basis for the annual increase in business rates. The British Retail Consortium says that today’s RPI inflation figure adds £350m to retailers' business rates bills.

Other rates determined by the September inflation figures include allowances and indexation for income tax, National Insurance, inheritance tax, capital gains tax, disability and maternity benefits, income support and tax credits.