Police are searching for a man after a sexual assault on a train between Putney and Mortlake.

British Transport Police (BTP) detectives have released CCTV images of a man they would like to question in connection with the assault which took place on May 15.

At about midday, a 24-year-old woman and a friend caught the train at Putney. A man sat opposite them and when the train arrived at Mortlake he stood up and touched the victim indecently.

The man, who had previously travelled to Putney from Clapham Junction, left the train and fled the station.

Detective Constable Andy Parkinson, of BTP’s Public Protection Unit, said: “We are treating this incident very seriously. This was a distressing and intimidating experience for the victim and we are determined to trace the person responsible.

“If you recognise the man pictured, or have any information about the incident that could assist us, I would like to hear from you.”

Anyone with any information about the incident should contact British Transport Police on 0800 40 50 40 quoting background reference B6/LSA of 02/06/11. Or call Crimestoppers anonymously on 0800 555 111.