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A Tube train derailed on the northbound Northern Line at Camden Town station in north London at about 1015 on Sunday morning. The last carriage came off and hit a wall.

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Seven people were taken to hospital - one had a broken leg and one had minor head injuries. None of the injuries was understood to be life threatening.

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About 200 passengers were led to safety by emergency crews. They said the tunnel was pitch dark and full of dust and debris.

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Eyewitness Harry Anscombe described passengers coming out in shock, and with blackened and bloodied faces.

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It is not yet known what caused the crash, although a track fault is suspected. Something falling off the train is another possibility.

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It is the second Tube derailment in 48 hours. A broken rail caused a crash on the Piccadilly Line on Friday. There were no injuries on that occasion.

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Questions are now being asked about the maintenance of the Tube, which was handed over to a private consortium at the beginning of the year.

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Lynne Featherstone, chairman of the London Assembly transport committee, said there appeared to have been a "catastrophic failure of the Tube's maintenance", and demanded answers.

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London Underground said the station was likely to be shut for about two days if the track was at fault, but "longer" if the train itself was the cause