A man has been handed a suspended prison term and seven years on the sex offenders register for masturbating in front of two 12-year-old girls on a busy commuter train.

Prasan Mahanty, of Bath Road, Cranford, was caught two years after the incident on a Kent train in April 2011.

Detective Constable Andy Parkinson, of British Transport Police's(BTP) Public Protection Unit, said: "Mahanty boarded the train at Chislehurst station and walked through the carriages to where two 12-year-old girls were sat travelling home from school. He sat opposite them, exposed himself and masturbated in full view of them.

"After realising what he was doing, the girls moved carriages and got off the train at the next station."

Despite issuing a media appeal, carrying out house-to-house enquiries and conducting plain clothes observations with the victims, officers were unable to find Mahanty until late 2013 when he was arrested for a separate offence and recognised by detectives.

DC Parkinson said: "This was repulsive behaviour by a sex offender who sought out children on a busy train for his own gratification. Today’s sentencing, several years after the offence took place, shows that we will never give up on bringing offenders to justice."

Mahanty admitted two counts of engaging in sexual activity in the presence of a child.

He was sentenced to four months in prison, suspended for two years and seven years on the sex offenders register at Blackfriars Crown Court on Thursday, January 8.

His case is part of Project Guardian, a long-term initiative to reduce sexual assault and unwanted sexual behaviour on public transport in London.

The joint project between BTP, Transport for London, the Metropolitan Police and the City of London Police focuses on increasing awareness and confidence amongst the public to report sexual offences.

Particularly those offences which are often unreported, like sexual touching, exposure, outraging public decency, lewd comments, leering and harassment.

BTP’s 61016 text number gives victims and witnesses a discreet way to report sexual offences. Offences can also be reported by calling BTP on 0800 40 50 40. In an emergency, always dial 999.