Rescuers say a 52-year-old German explorer who was injured in a fall deep inside an Alpine cave is well enough for the evacuation process to begin.

Researcher Johann Westhauser has been stuck a kilometre underground since suffering head injuries in a rock fall Sunday inside the Riesending cave system near the town Berchtesgaden in southern Germany.

Germany Cave Rescue

A rescuer rappels in the the Riesending cave system in southern Germany. Johann Westhauser has been stuck a kilometre underground there since Sunday. (Markus Leitner/Bayerisches Rotes Kreuz/AP)

The head of the rescue operation says doctors have given the OK for Westhauser to be stretchered out, a difficult process that will take days because of the narrow shafts and vertical lifting involved.

Andreas Wolf said Thursday that some 30 rescuers from Germany, Austria, Italy and Switzerland are in the cave preparing the evacuation.

Westhauser was spelunking with two colleagues when the rock fall happened some six kilometres from the entrance.