A man was seen 'jumping in and out of traffic' before a serious crash which shut the M3 for several hours, police have revealed.

The collision, which happened between 6.30am and 6.35am on the northbound carriageway, led to the road being closed between junctions 8 and 9 until almost 3pm.

Police are now appealing for witnesses to what happened.

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A spokesman said: "We're appealing for information after a man suffered life threatening injuries in a collision on the M3 this morning.

"We were called at 6.23am to reports of a man jumping in and out of traffic on the A33; which runs parallel to the M3. This was followed by a second call from a woman who had been driving on the A33 when a man jumped in front of her vehicle and tried to open the door.

"At some time between 6.30am and 6.35am a collision occurred on the M3 involving a car and a pedestrian, who matches the description of the man seen a short time before on the A33.

"The pedestrian has been taken to hospital in a life threatening condition. He remains in hospital at this time."

PC Haithum Zubaibi, said: “We are appealing for anyone who saw the man on the A33 or the M3 to come forward and speak to us. Were you driving in the area at the time? Do you have a dashcam fitted to your vehicle? If you have any information please come forward and speak to us.”

A 37-year-old man from Southampton who was arrested on suspicion of driving a vehicle whilst unfit through drugs has been released under investigation.

Anyone with information is asked to report online or call 101 quoting 44240369471.