Thames Valley Air Ambulance has provided an update on a serious motorway crash that has closed a stretch of the road. 

The air ambulance landed on the M40 at around lunchtime today (September 16) after a HGV overturned on the southbound carriageway near junction 10.

The stretch of the motorway between junction nine and junction 10 near Bicester is closed in both directions. 

READ MORE: M40 closes following serious crash near Bicester

A Thames Valley Air Ambulance spokesperson said: “We can confirm that our helicopter was dispatched to provide advanced critical care at an incident near Bicester earlier today.”

The air ambulance service is unable to confirm whether the incident is fatal at this stage.

Drivers are being asked to avoid the area as police warn of delays of an hour in both directions. 

Traffic is being diverted off the M40 at the exit slip road. 

Oxfordshire Fire and Rescue Service warned motorists to avoid the area if possible after "an accident involving a vehicle crossing the central reservation". 

OxonTravel, a traffic account run by Oxfordshire County Council, added at 1pm: "There has been a road-traffic collision on the M40 southbound on the J10 and a full closure is in place in both directions. 

"Thames Valley Police Roads Policing and Highways East are attending and arranging recovery.

"Please find an alternative route." 

Thames Valley Police has been contacted for comment.