The stock of unsold homes is rising steadily as the mood in the housing market darkens, but the array of properties is failing to tempt buyers back as homeowners demand ever-higher prices, according to Rightmove, the property website.

In its monthly survey of house prices, Rightmove said that the number of unsold properties was at its highest level for this time of year since it began to publish its survey in 2002. Each estate agent had an average of 67 homes on its books, up from 56 a month earlier, it said.

The website's figures also showed that asking prices had risen 0.8 per cent to £239,655 as homeowners try to push up prices. However, it estimates that actual selling prices have fallen 10 per cent since their peak last year.

Miles Shipside, the commercial director of Rightmove, said: “In the current market, sellers should price below their competition to achieve more interest now and avoid a larger price-drop later in the year.”

The company believes that as banks tighten their lending for mortgages, sellers must accept the new house price values quickly - or risk their home becoming unsellable.

The mismatch between what sellers will accept and what buyers can or will offer is most acute in London.

Sellers, used to a protracted housing boom, are struggling to understand how to price their home in a stagnant, or falling, market.

Lower sales prices are worst for those sellers who are downsizing or leaving the property market. Those who are upsizing can usually negotiate a more generous discount on the house that they are moving on to, dwarfing any “loss” on their existing home.

Mr Shipside said: “Most sellers seem to be ignoring the increased competition from other unsold properties and the challenge buyers now face in obtaining a mortgage.”

The unrealistic prices being asked threaten to cripple the market further, just as lenders are being reported as unwilling or unable to lend to scores of apparently creditworthy borrowers.

On Friday, The Times reported that several lenders, including the Bath and Earl Shilton building societies, had withdrawn all of their home loan products because they could not secure funding.

Yet the time that houses are on the market is falling - from 93 days to 82 days. Mr Shipside said that sales were being achieved, but at prices well below the peak of the boom.

Last week, the agents Hamptons International and John D Wood suggested that prices in some areas had fallen 10 per cent.

Asking prices are now on average only 5 per cent higher than a year ago. This contrasts with the real annual house price inflation of 2.7 per cent reported by Nationwide last month, a rate that has pushed the average house price up to £179,358.

Asking prices dropped below £225,000 in January, but have been recovering since.

Regional prices

In Wales, asking prices rose 3.5 per cent in a month.

Sellers in the West Midlands and East Anglia reduced asking prices by 2.9 per cent and 0.6 per cent, respectively.

Falls in London were sharpest at top and bottom. Kensington and Chelsea asking prices fell 4.1 per cent. Those in Redbridge fell 4.7 per cent.

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