Police have released the picture of a man they wish to speak with after a teenager was sexually assaulted on a train.

At about 4pm on June 29, a man boarded a Southern train at Balham station at the same time as the victim, an 18-year-old woman.

The man approached the victim and sat next to her, before sexually assaulting her.

He then left the train at Norwood Junction.

Officers believe the man in the CCTV image may have information which could help their investigation.

If you recognise him, or witnessed the incident, please contact BTP by texting 61016 or calling 0800 40 50 40 quoting reference 452 of 29/06/19.

Alternatively you can call Crimestoppers anonymously on 0800 555 111.