British Transport Police are appealing for information after a man was punched to the floor and had his iPhone stolen while travelling through Brentwood.

It happened between Thursday, December 13 and Friday 14, when the man, 35, was travelling home from a night out.

The victim, from Chelmsford, was unsure on which service the incident took place, but investigators believe the violence used by the men would encourage witnesses to come forward.

He boarded the train at Liverpool Street Station at about 11pm, and then changed services at Brentwood and Shenfield before heading towards Chelmsford.

Detective Constable David Bishop, the investigating officer, said: “At some point, two men approached the victim when one of them suddenly punched him in the head causing bruises and swelling to his forehead and right eye. They then went through his pockets before stealing his iPhone, cash and bank cards.”

Officers are reviewing hours of CCTV from stations and trains travelling between the stations in the area and are urging anyone who approached the victim and witnessed the assault to come forward.

DC Bishop added: “This was an unprovoked attack on a victim who was simply making his way home from an evening out with friends. He had his possessions stolen from him just weeks before Christmas and was left shaken and injured.”

Anyone with information is asked to contact British Transport Police on 0800 40 50 40 quoting incident number B6/LNA of 31/12/2012. You can also call Crimestoppers, anonymously, on 0800 555 111.