A caver has died in the Yorkshire Dales despite a 17-hour rescue operation to get him out of a pothole that involved almost 100 volunteers.

The Cave Rescue Organisation (CRO) said the incident happened on Saturday afternoon at Curtain Pot, on Fountains Fell, North Yorkshire.

A statement on the CRO’s website said the man, who was part of a group of three, broke his leg in a 6m (20ft) fall deep within the cave.

It said the narrowness of the passages in the unmapped exploration cave provided severe difficulties for rescuers and the man died before he could be brought to the surface.

The statement, posted on Sunday, said the man “fell approximately 6m down a pitch deep within the cave concerned, sustaining a suspected fractured femur”.

It explained how the other two cavers went for help before one returned to the casualty.

The statement said: “As an exploration site, the cave was not mapped, nor were the passages of sufficient width to allow extrication of an immobile casualty.”

It said initial rescuers realised that extrication would “require major engineering work simultaneously at many places along the length of the cave, as well as fully rigging for rescue” so the team called in reinforcements from a number of other groups in the region.

The statement said: “In the meantime the casualty was provided care by a team doctor assisted by trained casualty carers, who monitored his condition, as well as packaging him for the eventual extrication.

“Unfortunately, due to the nature of his injuries, and the extended time needed to create a navigable way out, the casualty succumbed to his injuries and died just prior to the extrication beginning.”

The CRO said the operation, which began just before 1pm, involved 94 volunteers for more than 17-and-a- half hours, including nearly 70 at the site itself.

The teams involved included Upper Wharfedale Fell Rescue Association, Swaledale Mountain Rescue Team, Calder Valley Search and Rescue Team, Cumbria Mines Rescue, the Bradford Pothole Club, the Yorkshire Spelio Society as well as members of the CRO’s reserve cavers list. It said a total of 1,626 volunteers’ hours were involved.

The statement said: “We would also like to extend our thanks to Yorkshire Ambulance Service and YAS HART team and to the Maritime and Coastguard Agency who remained in close touch in readiness to provide immediate air evacuation in the event of a successful extrication, which sadly was not to be.”