POLICE are appealing for witnesses after a collision on the M40.

At about 9.45am yesterday, two cars and two police motorcycles from Warwickshire Police, were involved in a collision on the M40 northbound between junctions 4 (High Wycombe) and 5 (Stokenchurch).

One officer sustained a serious leg injury and was taken to the John Radcliffe Hospital, Oxford, where she is still undergoing treatment. Others involved in the collision were treated at the scene for minor injuries.

The cars involved were a silver Mazda, and a black BMW which failed to stop.

If you have any information about the incident, please call Sgt Steve Madoc-Jones at Amersham roads policing department via the Police Enquiry Centre on 0845 8 505 505 or if you don't want to leave your name or speak to police, call the Crimestoppers charity on 0800 555 111.