Balfour Beatty Rail Maintenance admitted to Chelmsford magistrates on Tuesday that it had breached safety legislation last year.

Magistrates passed the case on to crown court for sentencing.

The prosecution followed an investigation by the Health and Safety Executive into the derailment of eight sections of a freight train between Witham and Kelvedon in Essex, on 23 September last year.

Balfour Beatty had been repairing parts of the track because of drainage problems.

The derailed train hit a bridge, showering bricks onto the road below and causing an eight vehicle accident.

No one was hurt, but 490m of London-bound track was destroyed, as was 220m of the track in the other direction.

Both lines were blocked for several days.