Four months after the Chancery Lane tube crash, London Underground has yet to pinpoint the underlying cause, a damning report says.

The London Assembly's transport committee released the report today, listing a host of concerns about the management and safety levels of London Underground.

At least 32 people were injured when a Central line train carrying 500 people derailed near Chancery lane station, on January 25.

Initial analysis shows the derailment was caused by a motor underneath one of the carriages breaking free, and the report says LU management already knew there was a problem with Central line trains.

"Overall, failure to identify the root causes of the problem after previous incidents on the Central Line, and concerns over maintenance practice, lead the Committee to believe that Chancery Lane was an accident waiting to happen," the report concludes.

The type of train used on the Central line is "inherently unreliable and performs badly", it adds.

The relationship between management and unions on the Tube is "close to paralysis", and safety concerns raised by union representatives were not fully investigated, the committee also says in the report.

One of the passengers on the train has spoken of people "screaming and panicking" as the train crashed off the tracks.

Winward Regis, of Stratford, boarded the westbound train near his home and noticed how it began stopping for longer periods at successive stations, with more noises coming from the carriages.

As the train headed from St Paul's toward Chancery Lane the train began to judder violently, and the lights went out.

"Glass was shattering and what looked like thick smoke came into the carriage. People were screaming and panicking," his evidence said.

The train stopped with some of the carriage next to the platform, and people were able to get off the train, although thick dust obscured exit signs.

Mr Regis and other passengers made their way upstairs to the street, where passengers were choking and coughing as emergency services arrived.