Pensioners have been hit hardest by the surge in the cost of food, fuel and mortgage bills, official figures show.

Those living on state pension benefits saw their living and housing expenses spiral by 5.1 per cent in the year to April, a much bigger jump than any other type of household, according to figures from the Office for National Statistics.

The sharp increase in prices for hard-pressed pensioners was far higher than the Bank of England's target measure of inflation, which was 3 per cent in April. Families with two children enjoyed the lowest increase in their bills, which jumped by 4.3 per cent over the year, the ONS said.

Pensioners have been particularly affected by the spiralling cost of energy and food because they spend a higher proportion of their income on them.

Howard Archer, of Global Insight, the economic consultancy, said that the pain was set to intensify: “Since April, food and utility prices have continued to increase, so things have got worse and will continue to do so as the recent energy price rises feed through to customers' bills.”

Food prices surged by more than 12 per cent in the year to July, while housing and utility costs rose by 7.6 per cent. The increasing pressure on households to meet the soaring cost of energy bills prompted Gordon Brown to announce last week a £1 billion package to help low-income and pensioner families to get free loft and cavity insulation, with a 50 per cent discount on such work for all other households. This, he said, could save each household up to £400 a year.

People living on their own have had to shoulder a sharper increase in their bills than couples, the ONS said. Bills for single occupancy households increased by 4.6 per cent in the 12 months to April, while couples saw their costs climb by a more modest 4.5 per cent.

The report comes as Mervyn King, Governor of the Bank of England, today gets set to write his second letter to the Chancellor to explain why inflation has risen so high. Figures released this morning are expected to show that inflation rose again in August after hitting a 16-year high of 4.4 per cent in July. Economists expect inflation to rise to 4.6 per cent, the highest level since April 1992.

Mr King must write an explanatory letter when inflation rises more than one percentage point above the 2 per cent target, and every three months thereafter, until it falls back below the 3 per cent threshold. He said last week that it would be “most surprising” if he did not have to write a letter today, which will be only the third such missive since the Bank of England was granted independence in 1997. Some analysts predict that he may have to write another letter at the end of the year. The Bank has forecast that inflation will rise as high as 5 per cent, before falling back sharply.

While the effect of rising prices differed markedly across different households, its effect, based on people's income, was more muted. The very poorest saw costs rise by 4.5 per cent over the year, with their expenses pushed up by increases in energy and food costs. The richest experienced a similar 4.5 rise, with their costs pushed higher by rising school fees and fuel bills.

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