1,000 Gambian villagers were abducted by "witch doctors" and forced to drink hallucinogens, an international rights group said on Wednesday.
Amnesty International called on the government of President Yahya Jammeh, who seized power in a 1994 coup and has claimed he can cure Aids, to halt the campaign and bring those responsible to justice.
Police officers, soldiers and some of the president's personal security guards accompanied the "witch doctors" in the series of round-ups, witnesses said. In the most recent incident, which took place on March 9, paramilitary police armed with guns and shovels surrounded the village of Sintet before dawn.
Amnesty quoted a witness as saying that security forces vowed "that anyone who tries to escape will be buried six feet under." The prisoners were then taken to Mr Jammeh's farm in his native Kanilai, east of the capital.
At the farm, the victims were "forced to drink unknown substances that cause them to hallucinate and behave erratically," the rights group said in a statement.
"Many are then forced to confess to being a witch. In some cases, they are also severely beaten, almost to the point of death."
The mysterious liquid prompted serious kidney problems in many of those rounded up, and two people died after being subjected to the ordeal, Amnesty said.
Mr Jammeh has said that he believes witchcraft was behind his aunt's death earlier this year, and has been inviting "witch doctors" from nearby Guinea to combat witches, the London-based rights group said.
In 2007, Mr Jammeh declared he had discovered a cure for Aids and began treating patients inside the presidential palace, using herbs and incantations. His dictatorial regime has cracked down harshly on critics, especially the press.
On March 8, authorities arrested Halifa Sallah, who has written about the "witch doctors" for the main opposition newspaper, Foroyya. The former presidential candidate has since been charged with sedition and spying, Amnesty said.