Police have launched a manhunt to find an attacker after a Central line passenger was violently punched several times.

British Transport Police (BTP) have released an image of a man they want to trace following the "nasty assault" on board an eastbound train between South Woodford and Woodford.

The 42-year-old man from Essex was left with a multiple cuts and bruises to his face and head after being punched repeatedly during the unprovoked attack on July 14.

He was treated for his injuries, including a cut to his lip by paramedics from London Ambulance Service at Woodford Station.

Detective constable, Michael Hatcher, said: "A 42-year-old man from Essex was sat on the train looking down at his mobile phone.

"Shortly before the train arrived at Woodford, a man assaulted him, punching him several times to the head and face.

"The victim alerted station staff who tried to stop the suspect but he made off, prior to police arrival.

"BTP officers conducted a thorough search of the area but nobody matching the suspect’s description was found.

"This was a nasty assault which left the victim with a number of injuries to his head and face.

"We treat all violent crime on the Underground with the utmost seriousness and are doing all we can to catch the person responsible.

"We are very keen to speak with the man pictured, as we believe he will be able to greatly assist the investigation.

"If you know who he is, or witnessed the incident and have not come forward to police, please get in touch."

Anyone with information should contact BTP on 0800 40 50 40, or text 61016, quoting reference T/B4 of 31/07/2015 or contact Crimestoppers anonymously on 0800 555 111.

East London and West Essex Guardian Series:

Police are keen to trace this man following the assault on July 14