A Tube derailment occurred after maintenance company Metronet failed to comply with measures laid down after an earlier derailment, a report claims.
The White City train derailed at a set of points
The train derailed on the Central line at a set of points on the approach to White City Station on 11 May this year.
The Transport for London report, which also criticised London Underground, said the design problem of new switch rails also caused the derailment.
Metronet said it fully supported the report's recommendations.
There were no injuries to the 150 passengers, who were able to leave the train within five minutes of the derailment.
Lloyd Rodgers, Metronet Rail BCV Infrastructure Director, said: "The report is critical of both London Underground (LU) and Metronet, and we will fully support the recommendations - which have industry-wide significance.
"For its part, Metronet is also investigating further the issues surrounding the communication of critical information."
The presence of a distinct wear pattern in a new switch rail, replaced during engineering hours the night before also led to the derailment, the report said.
'Good safety record'
The measures prescribed by London Underground after a derailment at Camden Town in October 2003 were designed to manage the risk of derailment associated with the replacement of the switch rail.
Seven people were injured in that incident.
The report criticises London Underground for inadequately monitoring Metronet's compliance with the measures.
LU's Central line service director Nigel Holness said:
"Safety is London Underground's top priority and the Tube has a very good safety record.
"It is very disappointing that, although specific measures were in place to avoid derailments at locations like the points at White City, a train was still derailed.
!"The report pulls no punches and has identified that Metronet's failure to fully comply with measures set out by LU was the principal cause of the derailment.
"It also concludes that LU did not undertake checks to ensure that the specific measures were being complied with, which must also be addressed."
Bob Crow, general secretary of the Rail Maritime and Transport union, said: "A company that fails to comply with explicit safety instructions put in place after one derailment and as a result causes another should not be allowed to continue operating on the network."
He added: "We have always said that the PPP (Tube privatisation) would lead to dangerous fragmentation and communications breakdown, and that is exactly what is happening."