Amnesty International has joined the family of two Filipino-Algerian sisters in appealing to Muslim militants to free the women seized several days ago in the southern Philippines.

Nadjoua and Linda Bansil were taken by about 10 suspected Abu Sayyaf militants Saturday in Sulu province while working on a short film about impoverished Muslim coffee farmers.

Linda Bansil wrote for Amnesty International publications in the Philippines and her sister volunteered work on films about Filipino tribesmen. They also worked together to produce low-budget, independent films showcasing Filipino Muslim life and culture.

The al-Qaida-linked group is notorious for ransom kidnappings and terrorist attacks. The militants are still holding a Jordanian journalist and two Europeans.