(AFP) - The United States said yesterday it was increasingly concerned about attacks by the Philippine-based Abu Sayyaf Muslim rebel group on parts of Malaysia's Sabah state.

The State Department warned US citizens to take "extreme caution" in the area and warned that the group had stationed detachments in places including the islands of Sipadan and Pandanan, where gunmen have previously carried out kidnappings.

"The region is remote and large in area, and assistance in security matters may not be readily available," the department said in a public announcement.

Relations between Manila and Kuala Lumpur have twice been broken off over the Philippine claim to Sabah, which dates back to 1704.

Malaysia now pays RM5,300 annually in what it calls cession money for the region.

The Muslim Abu Sayyaf group severely embarrassed the Philippines government last year when it launched a massive kidnapping spree on Philippine soil, and took large groups of foreigners hostage.

It still holds two captives an American, Jeffrey Schilling, and a Filipino.