UN human rights experts urged Israel to release Ahmad Manasra, a 20-year-old Palestinian who was imprisoned at the age of 14.
They said Manasra's mental health was deteriorating.
"Ahmad's imprisonment for almost six years has deprived him of childhood, family environment, protection, and all the rights he should have been guaranteed as a child," they said in a statement.
"This case is haunting in many respects and his continuous detention, despite his deteriorating mental conditions, is a stain on all of us as part of the international human rights community."
The experts appealed to Israeli authorities to free Manasra and allow him to go back to his family and get psychological counseling and support.
The statement said it was time for the "pervasive system of arrest and detention" conducted by Israel in the "occupied Palestinian territory" to receive international attention.
