Families had an extra £17 a week in their pockets to spend on treats in April compared with a year earlier, a report has found.

The average UK household had £187 a week of discretionary income in April, marking a £17 or 10% increase in their spending power on the same month in 2014, according to the Asda income tracker.

Air fares were 5.3% lower in April than they were a year ago, freeing up more extra cash for holiday treats, while food and non-alcoholic drink was 2.8% cheaper than a year ago, the report found. Home electricity, gas and fuel also saw a 2.8% annual decrease in price. Vehicle fuel costs were down by 12.3% annually.

Mortgage costs have edged up only slightly year-on-year, by 0.3%. A mortgage price war in recent months has seen many lenders battle it out to offer their lowest ever rates.

The falling cost of essentials is the "most significant" factor behind the growth in UK households' spending power, the report said.

It added: "Families are benefiting from a range of factors including a continued pick-up in wage growth, falling unemployment and a further increase in the income tax free personal allowance, which rose by £600 at the start of April."

The report said that a combination of the pick-up in wage growth and additional increases in employment boosted household net incomes by 2.9% in the 12 months to April.

Families' spending power is the spare cash they have available for "luxuries" such as holidays, cinema and theatre trips, dining out, toys, sports, gambling, computer software and games, once essential living costs such as food, clothing, transport, housing costs and bills have been taken into account.

The report is compiled for Asda by the Centre for Economics and Business Research (Cebr).

Office for National Statistics (ONS) figures recently showed that inflation turned negative for the first time in more than half a century last month.

Chancellor George Osborne previously hailed the ONS figures as "good news for family budgets". The Consumer Price Index (CPI) measure of inflation dipped to minus 0.1%, the ONS said.

Sam Alderson, an economist at Cebr, said: "With inflation turning negative in April, concerns have once again been raised about the effect of deflation on the UK economy.

"However, negative inflation is largely expected to be temporary. As such, the significant increases seen in household spending power should provide the economy with a major boost in 2015."