A major rescue operation is underway after a woman plunged about 30m down a cliff face in the Blue Mountains National Park.

Emergency crews were called to Ben Trovato Wall about 11am on Saturday after a woman, believed to be in her 30s, fell while climbing or hiking with a group of people.

NSW Ambulance said the woman suffered head and arm injuries.

Multiple crews are at the scene, including Special Operations paramedics and the medical team aboard the Toll Ambulance Rescue Helicopter.

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The woman was winched to safety hours later and was taken to hospital in a serious but stable condition.