Dealers are being warned to check the history of used cars due to rising numbers of insurance write-offs going on sale.

Since the beginning of 2005, nearly 400,000 vehicles have been recorded by insurers as written-off, having suffered extensive damage in road accidents and either deemed unsafe to return to the roads or uneconomical to repair.

However, AA Car Data Check has discovered that nearly 26% of these cars remained available in the used market.

Rob Whalley, managing director for Experian’s Automotive division, which supplies the data for the AA, said: "In 2005, 68% of all the cars involved in major accidents could be repaired, but the cost of repair was uneconomical when compared with the value of the car itself. These were classed as categories C or D write-offs and, while they are not dangerous to buy, their market value will have been considerably reduced.

"In the worst cases, however, customers could be buying a car that the insurance companies have classed as categories A or B, which are considered too dangerous to be repaired and returned to the road."