The number of homes sold by estate agents reached an 18-month high last month in fresh evidence that the housing market crash may be levelling out.

The average agent agreed 10 sales during April, up from eight in March and a low of just five last August, according to the National Association of Estate Agents.

The findings come as property website Rightmove said asking prices in England and Wales had risen for the fourth month in a row during the four weeks to May 9, increasing by 2.4 per cent.

The average property price on the site edged ahead to £227,441 in May from £222,077 in April but Rightmove.co.uk said the number of properties being put up for sale remained low. Just 61,000 new homes came on the market during the month, compared with 135,000 in May last year.

”The long-term worry is that the supply side of the housing market is now compromised for several years to come,” said Miles Shipside, commercial director of Rightmove. “Developers have shed much of their workforce so could struggle to increase capacity, and we are now seeing the lowest number of new sellers of second-hand homes for the month of May since 2003.”

The existing inventory of unsold stock remains stubbornly high, dropping to 71 from 72 per estate agency branch - suggesting a high level of effectively unsalable stock, with many sellers unable to reduce their prices further without compromising their ability to move.

“Equity-poor home owners are either not coming to market, or are having to price too high,” said Shipside and he warned the scale of the problem is potentially far worse now than in the 1990s downturn, as re-mortgaging was a relatively new development then.

He also said that with house prices so low, sellers are being deterred by falling loan-to-value ratios with those households that remortgaged to finance spending and recent buyers who are already in negative equity particularly badly hit.

Some households with 25 per cent equity are also being excluded from the market because they haven’t got enough equity to trade up.

However, despite the problems with supply, there are signs that activity in the housing market may have now passed its lowest point.

The Council of Mortgage Lenders last week reported a 29 per cent jump in mortgage lending to people buying a new home during March.

The Royal Institution of Chartered Surveyors also said inquiries from potential buyers rose at their fastest pace in almost a decade in April.