The woman was believed to have been subjected to a ceremony during which other sect members covered her with a blanket and sat on her, the daily El Pais said, citing sources involved in the investigation. The goal was to interrupt her breathing, the sources said.
The lack of oxygen causes the body to convulse and eventually to urinate and defecate, which the Paris-based sect sees as purification of the body that can lengthen a person's life, the newspaper reported.
But while taking part in the ritual Sunday in the town of Villajoyosa in southeastern Spain, the woman -- a mother of two in her 30s -- went into cardiac arrest.
Three Spaniards, including the woman's husband, were detained in connection with her death, police said.
State radio had said Monday the woman was involved in a satanic ritual, but the El Pais report made no mention of devil worship. The newspaper cited the victim's mother as denying her daughter belonged to a sect.