The injured man sustained leg and chest injuries as well as a concussion in a fall some 250 metres below the ground, while exploring a relatively uncharted section of the Jack Daniel's cave.

Rescuers have been as a priority stabilizing his medical condition, as well as making preparations to bring the explorer out through some very tight and difficult sections, in hazardous conditions.

The changing weather is an issue for emergency responders today. "We fear that at midday there will be a cold front on the way. Snowfall is expected at 2,000 meters above sea level. Right now, it's wet and cold up there", said mountain rescue spokesperson Maria Riedler.

During the night, communication with the team below ground has improved, as a telephone line was laid down to the rescue location.

The accident took place at 2 a.m. on Thursday morning, when the 27-year-old caver fell some seven metres down a steep cliff.  

The alarm was raised by his five colleagues, who were exploring the mostly-vertical cave for research purposes.

Rescuers have said that there is a difficult bottleneck which will make recovery of the injured man extremely challenging, but despite this they hope to be able to complete the rescue by Saturday afternoon.

Tennen mountains near Salzburg.  Photo: Hans Fischer

Weather in the region is deteriorating, however there was a brief period when a rescue helicopter was able to reach the area, to bring in much-needed supplies to the Laufner hut at 1,726 metres - from there, it's another 90 minutes' hike to the cave entrance, which is at 2,120 metres above sea level.

Currently, the rescue team is engaged in excavations to widen the most constricted sections of the cave, to allow the Pole to be removed while lying on a mountain rescue stretcher.  A specialist cave doctor is with him at all times, as there is a small team who are working in shifts to monitor his condition.

Many of the rescuers were also involved in the dramatic cave rescue in June of Johann Westhauser, who was recovered from Germany's deepest cave after being injured in a fall.

The Tennen mountains are known world-wide for their caves, including the Eisriesenwelt, the world's largest ice cave.

The Eisriesenwelt ice cave.  Photo: Eisriesenwelt Werfen Austria