A man driving a black cab sexually assaulted a teenage girl in his vehicle as he drove her home in Oxford.

Police are appealing for witnesses after a 17-year-old girl got into a black cab at Gloucester Green and asked to be taken to Jericho at around 11pm on Friday.

Officers said the girl asked to be taken to her home.

When they arrived at around 11.15pm and before she had a chance to get out of the cab, he drove off at speed.

He then took her to another location nearby, which the victim did not recognise, where he forced her to perform a sexual act.

Police said they are treating the incident as a serious sexual assault.

The taxi driver is described as Asian, 45-50 years old, overweight with a large belly. He also had stubble and black hair with flecks of grey.

He spoke with an Indian or Pakistani accent.

Dc Sarah Berry from Oxford CID said: "It is still not clear whether this was a licensed taxi driver or whether this man was posing as one.

"Either way, he has completely taken advantage of this young girl's trust when she was alone and vulnerable.

"Did you see this taxi speeding in the Kingston Road area? Or did you see a black cab parked up somewhere in the Jericho or Woodstock Road area at around midnight on Friday? Perhaps you recognise this man's description. This was a serious sexual assault, so please get in touch."

Anyone with information should contact police on 08458 505505 or speak anonymously to Crimestoppers on 0800 555111.