An accident is causing long delays on the M4 heading westbound this afternoon.
The accident has caused two lanes near Junction 7 to be closed, causing hour-and-a-half tailbacks between Junctions 4B and 7.
All lanes are now open again on the M4 westbound. But there are currently long delays between J4 and J5, due to congestion from the earlier incident at J7.
Road users are still advised to consider alternative routes and allow extra time to complete their journeys.
Thames Valley Police are appealing for witnesses to the accident which happened at 1pm. The Air Ambulance had to be called after reports that a motorcylist had come off his yellow and purple Suzuki motorcycle close to the junction 7 bridge.
The motorcyclist was airlifted to the John Radcliffe Hospital with life-threatening injuries.
The eastbound carriageway was also closed while the air ambulance was landing.
Sgt Carl Kneale, from the Joint Operations Unit for Roads Policing, said: “I am appealing for anyone who saw the rider fall off his motorcycle.
“I would also like to hear from anyone who saw the vehicle travelling prior to the collision.”
Contact investigating officer PC Kevin Rodney from Roads Policing via the 24-hour Thames Valley Police enquiry centre on 101 quoting URN 610 4/4..
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