Police would like to hear from witnesses to the crash between a cyclist and a car, or anyone who saw the driving manner of the vehicle or riding manner of the cyclist before the incident.
The cyclist, a man in his 40s, was first taken to the Queen Elizabeth Hospital in King's Lynn and last night transferred to Addenbrooke's Hospital in Cambridge with serious neck, pelvis and leg injuries for specialist care.
Emergency services were called at around 3.15pm yesterday to reports that a grey VW Polo travelling towards King's Lynn was involved in a collision with a cyclist who was travelling in the same direction.
The A149 at Queen Elizabeth Way between the Knights Hill Roundabout and the Castle Rising Crossroads was closed for almost four hours while police collision investigators worked at the scene. The road was reopened at 7.30pm.
Officers want hear from anyone who may have witnessed the collision or has any information that could help their investigation.
Contact PC Tom Allison at Swaffham Roads Policing on 101.
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