British Transport Police (BTP) are appealing for information after a man was assaulted on a train between Balham and Crystal Palace.

The 26-year-old was walking up the stairs at Balham station at around 9.20pm on April 20 when he was approached by a man who began to verbally abuse him.

The victim ignored the man and boarded the train, but noticed the man follow him into the carriage, where he launched an unprovoked attack.

Detective Sergeant Jane Hill, investigating officer, said: "This was a very busy service, and I am sure that someone would have seen this violent attack.

"It must have been a frightening experience for many of the passengers onboard and I’d like to assure them that we’ll do all we can to catch whoever is responsible.

"Incidents like this are extremely rare on the rail network and we are taking this investigation very seriously."

The man was with two other people who were not involved in the incident. Police believe he may also have connections to the Brentford area.

Anyone with information can contact BTP for free on 0800 40 50 40, quoting reference B4/LSA Alternatively contact Crimestoppers anonymously on 0800 555 111