A teenage schoolgirl was snatched off the street and sexually assaulted by two men in a silver car.

The victim, who was wearing her uniform at the time, was found knocking on doors in Oxford nearly four hours after she was abducted and driven away on Wednesday morning.

The girl is now in the care of specialist officers, Thames Valley Police said as they launched an appeal for witnesses and urged that parents ensure their children walked to school in groups.

The force said the girl was taken from the area of Marston Ferry Road and Banbury Road, Summertown, by two white men at around 8.25am on Wednesday.

She was found by officers over a mile away on Cavendish Drive, Marston, at midday.

Detective Chief Inspector Simon Steel of TVP Major Crime Unit, said: "We are in the early stages of this investigation and we are carrying out extensive enquires.

"But I would appreciate the public's help in relation to this very serious incident.

"This happened in what would have been a very busy area at this time of the day and I appeal to anybody who was in that area ... and saw an incident which matches the above report to call police immediately.

"It is possible you may have witnessed this incident and may not have realised the severity of the situation."

Superintendent Christian Bunt, local policing commander for Oxford, said the attack was a "very concerning incident for all involved and I appreciate that it must be very concerning for the public.

"In light of this we are stepping up patrols in the area to provide reassurance and there will be a very visible police presence whilst the investigation continues.

"I would ask parents to consider the safety of their children and if they are walking to school make sure they try to keep in groups.

"I would also ask people to remain vigilant and report anything suspicious".