The Cave Rescue Organisation (CRO), based at Clapham, North Yorkshire, were among 70 rescue volunteers who mounted a huge operation to help the group of 25 cavers after they became trapped in Ireby Fell Cavern.

North Yorkshire Police were alerted at 8.30pm on Saturday by a member of the public concerned her friends had not returned from a trip to the cavern, which is on the Yorkshire and Lancashire border between Ingleton and Kirby Lonsdale.

Further reports suggested a large party of cavers had become trapped in the system due to rising waters including two cavers who were stuck in a passage through a sump – a section of cave passage which is usually completely flooded.

Volunteers from Upper Wharfedale Fell Rescue Association and the Cave Diving Group helped with the rescue, which ended at 1pm yesterday when the final two cavers surfaced. One woman was treated for mild hypothermia.

Rae Lonsdale, of the CRO, said all but two of the cavers were confined in the main cave by floodwater and encouraged or hauled out as the flooding subsided.

"This left two people stranded beyond the sump. They were later dived through the sump by members of the Cave Diving Group and were able to make their own way out," he said.

Persistent concerns from the North East that a female caver was missing "somewhere in the Yorkshire Dales" were calmed by the eventual discovery that she was part of the Ireby Fell Cavern group.

Cave Rescue had to call on members of Upper Wharfedale Fell Rescue Association, Kendal Mountain Rescue Team and the Cave Diving Group to field what is believed to be a record number of calls on Saturday night, with further emergencies yesterday.

Earlier, at about 7.30pm on Saturday, volunteers helped seven cavers from Leeds who were trapped in Sunset Hole between a series of cascades near Chapel le Dale, north of Ingleton.

Mr Lonsdale said: "In the past we have twice had six cave rescues in one night but we have never had a group of 25 before."