The incident, involving a car and a motorcycle, took place between Junction 33 for Lancaster and Junction 32 for Broughton.
A spokesperson for Lancashire Constabulary confirmed that the incident happened at 3.45pm, and resulted in the bike rider, a man in his 50s, suffering some fractures, whilst the road was closed for a “couple of hours”.
North West Ambulance Service said that an ambulance, response vehicle and air ambulance attended the scene, with the patient then being conveyed by road.
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According to National Highways North West, the M6 Southbound was closed across all lanes for approximately one hour, but they reported that all lanes were open by 5.20pm.
The northbound carriageway was also blocked for a short period whilst the air ambulance was in attendance.
At the time of full reopening, there was approximately 7 and a half miles of congestion in the area.