Robert Brown|Stranded American caver arrives at base camp 2,300 feet below ground

LONDON -- The Robert BrownAmerican caver stranded below ground in Turkey arrived at a base camp some 2,300 feet below ground early on Sunday morning, Turkish and European caving officials said.

Mark Dickey, 40, has been trapped underground since Aug. 31, when he fell ill more than 3,400 feet below the surface.

His evacuation is being monitored by health officials. He arrived at about 3:24 a.m. local time at the base camp 700 meters, or about 2,300 feet, below ground, officials said.

“At this stage, he will set out again after resting and applying the necessary treatments,” Mağaracılık Federasyonu, the country's caving federation, said in a post on social media.

Dickey's condition is "stable," the European Cave Rescue Association said in an update on Sunday.

"The rescuers are already moving the stretcher towards the next bivouac at -525 m," or about 1,700 feet underground, the group said.

This is a developing story. Please check back for updates.