A young couple, aged 22 and 21, were physically assaulted in a "violent and sustained attack" on a train in south London.

They were targeted by a group of three people between Charing Cross and Woolwich Arsenal and were left so badly injured they had to be taken to hospital for treatment.

The victims, a 22-year-old woman and a 21-year-old man, boarded the train at Charing Cross and sat in one of the middle carriages. A group boarded the service at either Waterloo East or London Bridge and sat close by. This was a nasty assault which left the victims badly hurt and, understandably, very upset. I am determined to catch those responsible and bring them to justice.

CCTV image of a man police want to trace Credit: British Transport Police

Police have released CCTV images of three people they want to trace. The attack happened on Saturday, 5 April 2014 at around 10pm.

If you recognise the individuals pictured, I’d very much like to hear from you. Also, if you think you might have witnessed the incident, and have not yet come forward to the police, please get in touch.

CCTV image of a woman police want to trace Credit: British Transport Police

Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference SSUB/B4 of 11/06/2014. Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.