The rail faults that led to the Potters Bar crash, which killed seven people in May 2002, were 鈥渉ighly unlikely鈥� to be the result of sabotage, an independent inquiry has ruled.

Sabotage was the explanation suggested by track maintenance contractor Jarvis shortly after the incident. However, the report by the Rail Safety and Standards Board said that the derailment at the Hertfordshire station was unlikely to have been caused by a malicious act.

The report said: 鈥淔rom the evidence available, the panel has been unable to reach a clear conclusion as to how the front and rear stretcher bars [on the points] came to be in the as-found state 鈥� The possibility of a malicious act cannot be ruled out, although the panel considers this to be highly unlikely.鈥�

The report said that, although it had not been able to establish an underlying cause for the damage, it was concerned over the method used to ensure the locking of stretcher bar nuts. It also confirmed that the nuts were found to be missing from the set of points that caused the derailment.

The report said: 鈥淭he method in common use before the accident by maintenance and renewal staff for positioning and securing the nuts on adjustable stretcher bars has been shown to contribute to their loosening and could have been a factor in this case.鈥�

Len Porter, RSSB chief executive, said: 鈥淚t has taken a long time to thoroughly examine all the possible causes of this accident. Unfortunately the report does not provide us with conclusive evidence of any one cause. What it does point to is a combination of human and mechanical issues, plus a lack of proper maintenance procedure.鈥�