BANDA ACEH, Indonesia - An extremist Islamic group with alleged Al Qaeda has set up a relief camp on Indonesia's tsunami-stricken Sumatra island, raising concerns it could stir up sentiment against U.S. and Australian troops helping distribute aid.

The Laskar Mujahidin group posted a sign at its camp that read - in English - "Islamic Law Enforcement." Its members said Thursday they have been collecting corpses, distributing food and providing Islamic teaching for refugees here in predominantly Muslim Aceh province.

The presence of the extremist group, known for killing Christians in a sectarian conflict elsewhere in Indonesia, has generated fears that U.S. military personnel and others doing relief work could become terror targets.

It also underscores the fine line that foreigners, especially the U.S. military, must tread between being welcomed as Samaritans or viewed as invaders in a country where suspicion of outsiders runs deep...