There are delays of up to two hours on the M3 in both directions and on to the M27 this afternoon after a crash.
Hampshire Constabulary’s roads team tweeted that there had been a ‘serious’ collision, with ambulances also on the scene.
Traffic information service ROMANSE said there were delays of an hour in both directions approaching Junction 13 by Eastleigh.
Northbound traffic is tailing back onto the M27 until Junction 8 at Bursledon and Junction 4, and southbound on the M3 from Junction 9 at Winchester.
A Hampshire police spokeswoman said they were called at 3.24pm to reports of a collision between a Skoda Fabia and a motorcyclist.
The road was closed in both directions while emergency services attended the scene.
The southbound route has now reopened and one lane has reopened northbound.
A South Central Ambulance spokesman said the rider suffered a serious leg injury and was taken by road to the major trauma centre at University Hospital Southampton.