The type of Tube train involved in Saturday's derailment has been prone to mechanical problems, London Underground (LU) has admitted.

It said a faulty motor may have caused the accident and investigators were also checking whether the 800 passengers on the train could have breathed in asbestos.

At least 30 people were injured when the train jumped the tracks and hit a wall at Chancery Lane.

Tube crash facts

The entire Central Line may be closed until Tuesday Chancery Lane, St Paul's and Bank (Central Line only) stations closed for several weeks All 85 trains currently out of service The line normally has 500,000 passengers a day Disruption worse than after the 1987 Kings Cross disaster

LU said it was also looking at contact between the train and Central Line controllers, after the RMT union claimed the driver had reported a fault but was told to continue with the journey.

All the trains on the Central Line have been withdrawn from service and the route may remain closed until Tuesday.

Mick Rix, general secretary of the train drivers union Aslef, called for a public inquiry into the crash and said all safety work under the controversial Public Private Partnership should now be suspended.

'Routine check'

LU said its 10-year-old fleet of 85 Central line trains had been modified in recent years because of problems with their motors.

A spokesman said: "Each train is inspected every five days for that particular problem, as well as the routine check that takes place every morning.

"Yesterday's train had been checked for that particular problem two days before and there were no problems.

"It now seems that problems with the motor was a possible cause of the accident."

'Design fault'

RMT official Bobby Law, who was a driver on the line for 20 years, said there had been problems with the motors and the bolts that hold them on for two or three years.

The windows caved in and the doors opened in the tunnel and we were just bouncing up and down Marian Cassidy

Click here for more eyewitness reports

"It is basically a design fault. The bolts have come loose and that has meant that the motors have come loose," he said.

A spokesman for Bombardier, which delivered the train that derailed to LU in 1994, said it was of a design "running for 10 to 12 years now. There has been no major safety concerns as far as I know".

RMT leader Bob Crow said the train driver had earlier reported a fault with the train at Leytonstone station in east London, but was ordered to carry on.

LU said that drivers were responsible for their trains and could refuse to continue a journey if they thought there was a problem.

Terrified passengers

Launching the crash investigation after terrorism was ruled out, Mike Brown, director of stations for London Underground, said: "The priority is to get the causes of the accident as quickly and thoroughly as possible but making sure we leave no stone unturned."

The area where the train derailed

Mr Rix, said Aslef had repeatedly warned about potential problems with Central Line trains.

He said: "There should be an immediate public inquiry into all aspects of maintenance and safety on London Underground.

The train slewed off the line at Chancery Lane just before 1400 GMT, forcing the final few carriages into a wall and mounting the platform.

'Trapped inside'

Terrified passengers reported hearing screeching and banging from beneath the train in the minutes before the accident.

Passenger Marian Cassidy told BBC News: "People were trapped inside, the doors wouldn't open and people were trying to smash the windows."

She said that passengers were screaming as they walked from a carriage inside the tunnel, through an adjoining car and back on to the platform.

Other passengers said the train seemed to have been travelling fast before the accident and that the lights went out, plunging the carriages into darkness.

The driver was treated for smoke inhalation and was breathalysed, but the results were negative.

People who want information about casualties can call the incident line on 0870 0100 732.

Did you witness this incident? Send us your reaction using the form below.

I'm thankful to God that I'm still here Marcus Anderson, UK

I was on the platforms and suddenly there was this huge screaming and panic. Everyone including myself ran over to see what was happening. When I got there, it was a terrible sight, a train had gone off and hit a tunnel wall. I went over to ask the emergency services if I could help as I'm a doctor. But they refused. I'm thankful to God that I'm still here.
Marcus Anderson, UK

I was towards the front of the train, maybe the second or third coach. As we came into the station the train seem to be travelling a bit faster than normal and there was a loud banging noise as it slowed down. The driver came over the speakers and told us to leave the train and he shouted mayday, mayday! Most people you have interviewed have said how there was mostly calm. Not in my carriage - we fought for several minutes trying to get the door open with no success and there was complete panic. I even tried to kick the glass out but if just flexed. The locked doors were eventually opened by the station officer who was running up the train towards the rear of it, unlocking all the doors as he went. This was the most frightening experience in my life!
Chris, UK

I got on the train 3rd carriage from the end at Stratford Station. As soon as the train pulled away, there was an unusual loud sound, like a gush of wind travelling through the carriage. I thought at the time that this didn't sound right. This sound continued each time the train pulled away at each station heading towards Chancery Lane. As it left St Paul's the noise continued, and it was only when we approached Chancery Lane there was a loud rumbling noise, the carriage started to bounce up and down, people started screaming as the carriage lights went out.
Winward Regis, UK

People were looking out for each other Mark, UK

We have just got home; we were on the last carriage that got stuck in the tunnel. Although there were some screams and some understandably distressed people there were also people telling every one to stay calm. There was no pushing or shoving and people were looking out for each other, helping each other if needed. Everyone walked out in a surprisingly orderly way. Just thank God no one was seriously hurt.
Mark, UK

I boarded the train at Bethnal Green at about 1.40pm. There was a louder than "screeching" sound as we left the station. This seemed louder as we arrived and left Liverpool Street. I changed trains at Bank. There appeared to be the smell of burning as the train left the station. The noise was very loud. Another passenger was commenting on the smell to a LUL staff member as I left the platform.
Vineet Wadehra, UK

My fianc�e and I were on the Central Line platform as the derailing train approached. We had just picked up her engagement ring in Hatton Garden and were on our way to the London Business School for her afternoon class. The train seemed to rip through the station. As soon as I saw the doors fly off the train car, as it came around the corner into the station I knew it was time to get out of the station. My fianc�e and I are so happy to be alive.
Jason Josefs, UK

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