A woman is in hospital with head, spinal and rib injuries after having to be cut free from a car that rolled down a 30-metre bank and into a swamp in South Taranaki this morning.

Emergency services were called to the scene on State Highway 3, just north of Te Roti Road, just after 9am on Sunday.

Police say a 67-year-old lost control of the car she was driving and rolled down a 30-metre ban, landing on its wheels in a swamp.

The woman was cut free from the vehicle and taken in a serious but stable condition toTaranaki Base Hospital by the Taranaki Rescue Helicopter with injuries to her head, spine and ribs.

SH3 was reduced to one lane for a short period but is now fully open with traffic flowing normally.

Police are continuing to investigate the cause of the crash.