Some of the fiercest Muslim rebel commanders in the southern Philippines are in Manila to be sworn in as administrators of a new Muslim autonomy region in a delicate milestone to settle one of Asia's longest-raging rebellions.

President Rodrigo Duterte will lead a ceremony Friday to name Moro Islamic Liberation Front leader Murad Embrahim and some of his top commanders as administrators of a transition government for the five-province Bangsamoro region.

About 12,000 combatants are expected to be demobilized starting this year under the peace deal.

The Philippines and Western governments and the guerrillas see Muslim autonomy as an antidote to ease nearly half a century of Muslim secessionist violence, which the Islamic State group could exploit to gain a foothold.