Commuters were warned to expect significant disruption today after an express train travelling to Paddington station in London derailed close to the end of its journey.

Hundreds of passengers were evacuated from the First Great Western train after a set of wheels on one of the carriages left the track close to West Ealing station in west London at about 8.05pm.

Witnesses described how the train violently jumped as part of the carriage left the tracks but all coaches on the service from Swansea remained upright and there were no reported injuries.

Railtrack and the Health and Safety Executive are investigating. Police said there was no evidence of vandalism.

Passengers reported seeing the derailed carriage fill with smoke after feeling a sudden bump. Andrew Walker, 38, a journalist who was in another carriage, said: "It was quite strange, you do hear these kinds of sudden bumps but it was considerably greater than that and it was disquieting to feel the train dragging along."

About 500 passengers were helped off the train and taken on to Paddington after first being checked by emergency services.

A Railtrack spokesman warned that there would be "quite significant disruption" to services this morning.