Three individuals suspected to be Islamic State militants en route to Marawi City were nabbed by authorities in Sabah, a report by Jiggy Manicad on QRT said Monday.
Two of the suspects are Indonesian while the third is Malaysian.
Joint Task Force Tawi-Tawi confirmed the trio's affiliation with ISIS. The military, however, did not specify the exact date of the arrest.
The task force has since warned Mindanao residents that anyone proved coddling terrorists can face heavy criminal charges.
Soldiers in Marawi City have reported seeing foreigners fighting alongside the Maute group in the frontline.
The Indonesia government had earlier deployed fighter jets and additional policemen in northern Borneo to beef up security in case Maute members attempt to flee to the country.
The Philippines, Indonesia, and Malaysia also launched trilateral patrols against terrorism. — Joseph Tristan Roxas/BM, GMA News