A female passenger was sexually assaulted after falling asleep on a train in Essex. The 23-year-old victim was heading to Southend after getting on the service at Liverpool Street.

We now believe the man boarded a train from Shenfield to Prittlewell before getting onto the train with the woman. Detective Constable Paul Cudby, British Transport Police

CCTV image of a passenger police are trying to trace Credit: British Transport Police

We have analysed onboard CCTV footage of the incident and are keen to speak to the man in the pictures. Detective Constable Paul Cudby, British Transport Police

CCTV image of a passenger police are trying to trace Credit: British Transport Police

The attack happened on a train travelling between Prittlewell and Southend Victoria station at around 12:50am on Friday, 25 July.

CCTV image of a passenger police are trying to trace Credit: British Transport Police

Anyone with information can contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference ESUB/B12 of 25/07/2014.