TOULOUSE, France, Jan 23 (AFP) - A 48 year-old Frenchman who went missing last month has been found emaciated but alive in an underground cave system where he spent 35 days in pitch blackness eating nothing but wood and clay, police said Sunday.

Jean-Luc Josuat-Verges, a care-worker from Vic-en-Bigorre in the foothills of the Pyrenees, left home on December 18 saying he was depressed and wanted to be alone for a time, according the Depeche du Midi newspaper which broke the story.

Taking a bottle of whisky he drove to an abandoned mushroom farm consisting of a vast complex of underground galleries. But in the total darkness he became disoriented and was unable to find his way out.

"I kept looking for a week," Josuat-Verges told the Journal du Dimanche newspaper Sunday. "It was truly terrible fumbling around with nothing to eat. Luckily the walls were dripping with water so I could drink."

Josuat-Verges then determined to sit it out and wait for the rescue services.

"It was the survival instinct that saved me. I never panicked. I even sang a bit. I found some old plastic sheets which I wrapped myself in and then I went into a corner from which I did not budge.

"There was no food so I sucked bits of limestone for the minerals, as well as decomposing wood and lumps of clay. Hunger was never a problem, unlike the cold and the damp," he said.

On Thursday a group of teenagers taking advantage of a teachers' strike went to explore the mushroom farm - which is off-limits to the public - and saw Josuat-Verges' vehicle. They alerted police, who sent in a search party and found him the next day only 200 metres from the entrance.

Though tired and wasted, he had the strength to place himself on the stretcher before being taken to hospital, where he spent only a few hours under observation before returning to his wife and sons.

"It was like seeing a mummy rising from the dead," said one of the policemen who found Josuat-Verges, reported the Depeche du Midi which dubbed him "Le Miracule des tenebres" - "The miracle survivor of the darkness."