DETECTIVES cordoned off part of Gloucester Green, Oxford, yesterday after a woman told police she had been sexually assaulted.

The alleged incident happened at 11.30pm on Saturday in the alleyway linking Gloucester Green and the bus station, near Harveys sandwich bar.

The woman reported the attack to the police shortly after midnight, and was being interviewed by detectives yesterday as scenes-of-crime officers carried out a forensic search in the sealed off area.

Thames Valley Police press officer Toby Shergold said it was too early to say if police were dealing with a rape allegation.

He added: "The woman is talking to detectives so that we can ascertain the precise nature of the allegation. She contacted us shortly after midnight to complain that a serious sexual assault has taken place and we are now investigating.

"People out in Oxford on Saturday night who were in the area at the time may have seen something happen and we would urge them to contact us on 08458 505505."

Mr Shergold added that detectives were also checking footage from CCTV cameras in the area.

The woman's age has not yet been revealed. Mr Shergold was unable to say precisely how the woman reported the crime, or give more details about how she managed to escape.

He added that police were trying to build up a detailed description of her attacker.