Credit crunch doubles average deposit needed to buy a home to almost £40,000

At this level, a worker earning the average salary of £23,750 would need to save more than two years' take-home pay.

The study, from the mortgage adviser Mform.co.uk, found that in August last year, an average deposit of 11.75 per cent was required for the best deals. Today, it has risen to 20.75 per cent.

Expensive: Homebuyers may be put off by the massive deposit needed

With an average house price of £180,800, this means a buyer would need a deposit of £37,512, compared with £21,000 last year.

Those who have recently bought a home but did not put down a big deposit and need to remortgage will also be caught in the trap. If their mortgage is worth 80 per cent or more of the value of their home, they too will be refused the cheapest deals.

It comes as figures from the British Bankers' Association showed the number of owners remortgaging has crashed to its lowest level for seven years.

Just 54,232 managed to switch from one lender to a rival in July.

The worst hit are those who borrowed 95 per cent or more of their home's value and are effectively stuck with their current lender.

Meanwhile, the number who managed to get a home loan in July was 22,448, 65 per cent lower than in the same month last year.

The Royal Institution of Chartered Surveyors warned the figure is far too low to stop house prices from falling further.

The biggest losers are people who borrowed 90 per cent or more of their property's value who are effectively stuck with their current lender.

The grim figures emerged as housebuilder Bovis Homes reported a massive 80 per cent slump in its half-yearly profits.

Mform.co.uk said lenders were demanding bigger deposits as they grow more risk-averse and scale back the loan-to-value ratios they will advance.

The £37,119 deposit to buy the average house is 43 per cent more than the £20,980 needed last year even the the price of homes has been falling.

Francis Ghiloni of mform.co.uk said: 'First-time buyers or those who have entered the property market recently will struggle to qualify for the most competitive rates.'

The size of deposits has risen most for two-year fixed-rate mortgages, on average soaring from 10 per cent a year ago to 23 per cent now for leading rates.

But would-be buyers also need an average deposit of 22 per cent of their home's value to get a leading three-year fix and 20 per cent to get a top five-year one.

Those in London need to amass most - £71,616 to buy an average-priced home of £345,000 - and buyers in the South East need £46,843.

But even in the North of England, where property is cheapest, borrowers are having to find £28,000 to qualify for a leading mortgage rate.