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A manhunt is underway after a teenage girl was sexually assaulted on a train to London Victoria.

The 15-year-old victim was attacked by a man on board the service at around 3.10pm on Wednesday, August 5.

He seriously sexually assaulted the girl before getting off the train at Gatwick Airport, police said.

British Transport Police has released a CCTV image of a man who they would like to speak to.

Detective Inspector Ciaran May said: 'We're launching an urgent appeal following a very serious incident on board a train this afternoon.

'I'd urge anyone who recognises the man in the photo to get in touch with us as soon as possible.

'Likewise, if you were on the train at the time and witnessed anything which may be useful to our investigation, please get in touch. You can text us on 61016 or call 0800 40 50 40, quoting reference 469 of 05/08/26.'

British Transport Police has released a CCTV image of a man who they wish to speak to