Detectives investigating a sexual assault on a 15-year-old girl at last year's Derby have spoken to several people matching the description of the offender.

Detective Constable Ian Cherrington, said that officers were at this year's Derby on Saturday and spoke to some of the 120,000 racegoers about the attack including several who matched the description given by the victim.

She was attacked in woodland near the fairground and music area of Epsom Downs Racecourse at about 4pm on Derby Day in 2012.

Det Con Cherrington said: "Officers are now in the process of going through the intelligence gained on the day in the hope that it will progress the investigation."

Crimestoppers have offered a reward of up to £3,000 for information leading to the arrest and conviction of the attacker.

The attacker was a skinny teenager, aged between 16 and 17, is described as pale and spotty with a muscular build, prominent wide jaw and short gingery blonde hair.

He was wearing a dark blue top with long sleeves and baggy blue jeans.

Earlier in the day he was accompanied by another teenager of a similar age who had a larger build and short flattened brown hair.

This youth is believed to have inflicted minor cuts and bruises on a second teenage girl in the same area.

He was tanned and wore a white top and blue baggy jeans.

Det Con Cherrington said: "This is a complex investigation and I continue to urge anyone who has any information which may assist us in finding the person responsible and help bring them to justice to contact us.

"We are able to eliminate anyone not connected to the serious sexual assault and officers will treat all information passed to them in the strictest of confidence."

Anyone with information should call police on 101, quoting reference EP/12/2172, or Crimestoppers anonymously on 0800 555 111.