Faulty points like those that caused a fatal train crash in Cumbria were uncovered in other parts of the rail network, a report has revealed.
Failures in the points put one of the rails in an unsafe position
The Rail Accident Investigation Branch (RAIB) findings echo a Network Rail report, which revealed the 2B points caused February's Grayrigg derailment.
In response to RAIB safety advice, Network Rail examined 120 further sets of points, carrying out repairs to six.
One woman was killed and 89 hurt when a Virgin train derailed at Grayrigg.
Wednesday's report from the RAIB deals with much of the ground already covered in the joint Network Rail report into the accident published last month.
The RAIB said it had not yet fully concluded "the causal and contributory factors of the derailment" and added it hoped to publish another report in the early part of 2008.
Margaret Masson was killed when the train plunged off the track
It said the immediate cause of the accident was 2B points being in a deteriorated and unsafe state.
As a result of the initial investigation, the RAIB issued urgent safety advice on 6 June 2007 to Network Rail, and also to Nexus, Northern Ireland Railways and London Underground, who all use a similar design of points.
As part of their response, Network Rail undertook a further examination of the 120 sets of points most similar to 2B points.
Some faults were found, and in six cases, Network Rail imposed speed restrictions until faults to the track gauge, free wheel clearance and stretcher bars were rectified.
Failings in the stretcher bars were a major factor in the Grayrigg derailment and also in the 2002 Potters Bar crash, which killed seven people.
However, the RAIB stressed that the design of the stretcher bars at the two sites was "substantially different", and said it would consider the relevance of Potters Bar in its final report.
September's Network Rail report into the Grayrigg crash also found systematic failures in track patrolling and management.
In July, British Transport Police arrested a 46-year-old Network Rail employee from the Preston area and questioned him on suspicion of manslaughter.
He was released on bail until 31 October.
Margaret Masson, 84, from Glasgow died when the London to Glasgow Virgin Pendolino service derailed on 23 February.
Driver Ian Black suffered neck and shoulder injuries.