Muslim extremists who support Islamic State have staged a jailbreak in the southern Philippines, freeing eight of their fellow radicals.

Officials say at least 20 heavily armed members of the Maute militant group raided the jail in Marawi Saturday, allowing at least 15 detainees who are not members of the group to also escape.

The eight Maute members who escaped were recently arrested by soldiers who found a homemade bomb in the rebels' van at a security checkpoint.

The Maute radicals have frequently been seen carrying the black flag of Islamic State.