Union warned Railtrack

The use of contractors and subcontractors - many unqualified - has alarmed unions and MPs.

The rail unions have constantly campaigned for all maintenance of the national network to be brought back "in house", where it would be carried out by people employed directly by Railtrack.

Railtrack's chief executive John Armitt had refused to countenance this, but a few days before the crash he said he had become deeply worried that the use of casual, unqualified labour was jeopardising safety.

In an interview with The Times he said: "There's always a tendency, particularly in construction-related industries, to take a short cut and try and do a job more quickly.

By encouraging contractors to employ more direct labour rather than relying on an agency to send them along at the last minute, the likelihood of [accidents] is reduced."

At present Railtrack employs a number of specialist companies - including Jarvis Rail, responsible for maintenance in the Potters Bar area, and Balfour Beatty, in charge of the track at the time of the Hatfield tragedy in 2000. Some companies subcontract the work to casual labour, some of whom are said to be untrained and with no knowledge of rail industry safety procedures.

A recent Health and Safety Commission report expressed disappointment that key recommendations on use of contractors made by the official inquiry into the Paddington rail disaster have not been implemented on time.