Investigators have identified a track 'irregularity' near the site of a train derailment in East Sussex last week, leaving 20 people needing hospital treatment.

The Rail Accident Investigation Branch said on Wednesday that CCTV footage obtained after the derailment of a London Victoria to Eastbourne service on Thursday August 13 showed 'a track geometry irregularity existed on the immediate approach to the point of derailment'. In an interim report, investigators also said they had observed marks 'consistent with the wheels of the derailed rear vehicles having climbed over the rails'.

The embankment on which the railway runs was not found to have experienced any 'significant' slip prior to the accident, though investigators found 'evidence that some movement had previously taken place'. Around 150 people were on the train when it derailed, with 30 sustaining injuries and 20 requiring hospital treatment, they said.

The officials added that the investigation will consider a number of potential issues, including the sustained hot weather at the time. On Friday, a second passenger train derailed, with a Greater Anglia train coming off the track at Wickford in Essex. This is a developing story.