The average family has seen its disposable income drop by more than £150 a year, despite tumbling inflation, as tax bills rise and wages drop, figures suggest.

Families had an average of £143 a week left to spend on non-essential items, such as holidays, eating out and going to the cinema once they had covered their bills last month, down from £146 in January last year, Asda's monthly income tracker shows.

Charles Davis, economist at the Centre for Economics and Business Research (CEBR), who compiled the figures from Asda, said: “Downward pressure on discretionary incomes is coming from rising unemployment and weaker earnings growth. This is one of the key reasons why families are still worse off than a year ago, on this measure.”

Unemployment soared close to two million between October and December, the most recent official figures show, and economists predict that more than three million could be out of work by next year — the highest level since 1986.

While the average income for families rose from £657 to £680 a week, a bigger proportion was eaten up by taxes and basic expenses. And although inflation is now falling, the effects of last year's sharp rise in consumer prices is still being felt by homeowners, with essential costs such as mortgages and groceries rising by £23 over the past year.

More than a third of Asda customers are looking at ways to supplement their family income, separate figures show. A survey of 10,000 customers showed those looking to increase their spending power were working extra shifts, making their own clothes and selling possessions on eBay.

Households in Northern Ireland and the South West of England are being squeezed the most, with average weekly disposable incomes in these areas dropping by 3.2 per cent and 2.7 per cent respectively. Northern Irish households are spending £6 more on utility bills per week and £7 a week more on food. Consumers in the South West have seen their food bills rise by £7 a week, or nearly £30 a month.

Philip Hammond, the Shadow Chief Secretary to the Treasury, said: “This report shows how the recession is squeezing family budgets still further. And while the Government goes on a borrowing binge, stagnant wages and fear of unemployment mean ordinary families are likely to continue tightening their belts throughout 2009 as they struggle to make ends meet.”

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