CCTV images have been released after a 15-year-old girl was sexually assaulted on a train.

British Transport Police has released the images of three men who may be able to provide information on the attack.

The schoolgirl boarded a train from Gillingham to Gravesend at 8.15pm and was approached by three males who then seriously sexually assaulted her.

The first man was black, aged between 18 and 19 and wearing a black woolly hat.

The second was also black and wearing dark clothing with his hair styled in small twists.

The third man was white, aged between 18 and 19, and also described to be wearing a black woollen hat.

Detective Sergeant Andy Parkinson says the men had a Staffordshire bull terrier with them on the train.

He said: "Members of the public who may know who these men are should contact us, as we believe these men may hold crucial information about this offence and may be able to assist us with our inquiries."

Anyone with information on the October 8 incident is asked to call the witness appeal line on 0207 391 5275 quoting reference number B5 9/10.