Palu, Indonesia: An Indonesian shaman has been arrested for abducting a teenager and keeping her as a sex slave for 15 years by claiming he was possessed by the spirit of her imaginary boyfriend, police said on Wednesday.

The distressed woman, who is now aged 28, was found naked by police on Sunday in a jungle cave near the village of Bajungan in Central Sulawesi province.

She was reported missing by her family in 2003, when she was 13, after visiting the shaman for treatment of an illness.

The victim's father spent years looking for his daughter.

But police said the shaman, whose son is married to the victim's sister, had told the family the girl had gone far away and would not return.

"Every day, for many years, the shaman had sex with her under the pretense he was possessed by a male spirit," local police chief Iqbal Alqudusy told AFP on Wednesday.

The 83-year-old shaman, identified as Jago, tricked the woman into believing the spirit of a young man named Amrin lived inside him, Alqudusy said. The victim was convinced Amrin was her boyfriend.

The shaman is alleged to have hidden the woman in the cave during the day and to have had sex with her in a nearby hut at night.

Police rescued the woman, who is currently at a safe house, after receiving a tip-off from a family member.

"She is very disoriented, she's scared of people and keeps wanting to go back to the cave," Alqudusy said, adding she would undergo therapy.

The shaman faces 15 years in prison for allegedly having sex with a minor. His family members are also being investigated for failing to inform police.

Indonesia is a mainly Muslim country but superstitious practices are still widespread.

People often turn to shamans, practitioners seen as having influence in the spirit world, and the paranormal to treat illnesses or to consult on everyday life.

Authorities have introduced a law to ban black magic, with violators facing up to three months in jail or a fine of 450,000 rupiah (Dh150).