The union spoke out as the disaster put the spotlight on safety across the railway network.

Alan Johnson, chairman of the Carlisle branch of the RMT, whose members include the track maintenance and inspection staff who work in the Grayrigg area, said Network Rail, which has responsibility for the track, had cut maintenance by 30 per cent over the last year.

Officials at the organisation have defended their safety regime, but Mr Johnson said: “Network Rail have been going through all areas to see what maintenance needed to be done and three weeks ago they sent a hit-squad to Carlisle because it was one of the worst areas for maintenance.

“There was a backlog of maintenance work that needed to be done and that was because of the number of defects that been found and not touched. That’s happened because we just haven’t got the bodies to do the job.”

It has also emerged that a Network Rail inspection train took pictures of the track at the crash site just two days before the derailment.

Mr Johnson went on to claim that the current Network Rail track inspection regime is not sufficient to identify and address problems of the kind that may have caused Friday’s crash.

The company has confirmed that it carries out weekly line inspections, but Mr Johnson said that the increased volume of rail traffic, together with the increased speed and weight of trains meant lines should be inspected two or three times a week.

He said: “We’ve got high-speed trains, an increase in passenger numbers, increased train weights, yet we now have fewer track inspections.

“You don’t know when a defect is going to come up, whether it’s vandalism or something else, so weekly inspections are not enough. The track should be patrolled two or three times a week. I’ve been in the rail industry for 30 years, and when I started in 1977 the track was patrolled on four days in every week.

“Any defects were reported back to a sub-inspector who arrange to have them sorted out with other staff. That happened throughout the entire rail network. Then they reduced it to three times a week, then two times a week, and just after privatisation it went down to once a week.

“Since then, speeds have gone up 25 per cent and engineering trains which ran at 45mph are now running at 60mph and the weight of trains has gone up around 600 tons to as much as 1,800 tons.

“The number of trains has also increased. So why when the infrastructure is getting such a hammering are they still only patrolling the line once a week?”

Kate Snowden, of Network Rail, suggested that now was not the time to be discussing the track inspection regime, but she added: “We have a very rigorous maintenance regime, which includes a weekly [line] inspection where inspectors walk up and down the track to check that everything is as it should be.”

She said that Network Rail takes safety very seriously. Other aspects of the maintenance regime include the new measurement train; monthly maintenance checks; a quarterly inspection; and an annual inspection.

Network Rail yesterday refused to comment on the claims they were struggling to deal with a backlog of work and that maintenance had been cut by 30 per cent – elements which could form part of the inquiry into the accident.