The accident happened in Bamble, more specifically at Tegdalsåsen near Valle.
The climber, a man from Skien, is said to be critically injured after a fall.
Assignment leader in the southeastern police district, Vegard Møane, says VG that the patient is carried out from the scene of the accident.
– He is described as critically injured and will be flown to Ullevål Hospital, he informs the newspaper.