CHIANG RAI: The 12 boys rescued from a Thai cave were passed “sleeping” on stretchers through the treacherous passageways, a former Thai Navy SEAL told AFP yesterday, giving the first clear details of an astonishing rescue mission that has captivated the world, reports AFP.

The nerve-shredding three-day operation ended on Tuesday with the final group of four boys and the coach emerging from the cave which had held them captive for 18 days.

The rescue sparked jubilation with Thais heaping praise on the rescue team of foreign and local divers as the triumphant tagline “Hooyah” pinballed across social media.

But Thai authorities have been coy on how a group of boys, many of whom could not swim and none with diving experience, could have navigated the treacherous narrow and submerged passageways of the Tham Luang complex, even with expert diving support.

The dangers of the rescue were brought into sharp relief last Friday by the death of a retired Thai Navy SEAL as he ran out off air in the flooded cave complex as the extraction plans were being laid.

After days of mounting speculation, another former SEAL diver revealed the boys were sleeping or partially-conscious.

“Some of them were asleep, some of them were wiggling their fingers... (as if) groggy, but they were breathing,” Commander Chaiyananta Peeranarong told AFP.

“My job was to transfer them along,” he said, adding the “boys were wrapped up in stretchers already when they were being transferred”.

Junta leader Prayut Chan-O-Cha on Tuesday said the boys had been given a “minor tranquiliser” to prevent anxiety inside the narrow, twisting passages, many of which were submerged.

But he denied they were knocked out for an operation the rescue chief had called “mission impossible”.

Thai authorities imposed a media lockdown during the evacuation, even holding large white umbrellas around the boys as they lay in stretchers outside the cave as they were transferred to helicopters bound for hospital.