Tracks are being investigated after the Hatfield crash

The report, commissioned by the Rail Regulator and the Health and Safety Executive, blamed rising traffic and falling levels of rail renewals over the last 30 years for the problem.

Worsening track quality and greater reliance on manual ultrasonic rail inspection were also cited as causes.

"In terms of broken rails removed per year per track mile, Railtrack appears to perform significantly worse than the comparison passenger railways, and at a similar level to typical North American freight railways that carry much higher axle loads," it said.

In a joint statement the Rail Regulator and the HSE said Railtrack must "urgently examine and develop improvements" into how rails are inspected and tested for defects, how defects can be better identified and recorded, and when identified, how they can be better managed.

They also said Railtrack must examine its own guidelines for dealing with identified broken rails.

"Total numbers of defects in track should be reduced," the statement said.

Improvements under way

Rail Regulator Tom Winsor said: "Railtrack has been taking many of the actions necessary to reduce the number of broken rails and already has in hand a number of the recommendations made in this report.

"The report does, however, demonstrate that there are other methods, actions and processes available to Railtrack that could contribute to greater reductions in broken rails than the company is currently forecasting."

Railtrack chief executive Gerald Corbett said last year the firm introduced a �100m programme to reduce broken rails.

"The initiatives we've taken have seen a 30% drop in the number of broken rails so far this year," he said.

"This is a constructive report with positive ideas about how we can continue to improve our performance."