Instability and the easy flow of weapons have made Mindanao and nearby Philippine islands attractive to extremist groups, said speakers at the Milipol conference on homeland security in Singapore.
"Currently, IS is moving towards creating a territory in southern Philippines. The most recent communication issued by IS has announced that they have formally declared an East Asia division of IS in the southern Philippines," counter-terrorism analyst Rohan Gunaratna told the conference.
"The instability in the southern Philippines and the availability of weapons, internal displacement, refugee flows... Create the ripe conditions for foreign terrorists to come," he told AFP after his speech.
Singapore's Home Affairs Minister K. Shanmugam also told the conference that the southern Philippines "is becoming an area that is difficult to control despite the best efforts of the Philippine government".
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"So that is an area that can serve as a sanctuary for returning fighters from the Middle East. It can be a place where would-be terrorists can go... They can train, arms seem to move fairly easily into that area," Shanmugam added.
But as IS suffers battlefield setbacks, officials and analysts fear these fighters would return to their home region.
Southeast Asia suffered its first IS-linked attack in January last year when extremists launched a deadly suicide bombing and gun attack in Jakarta.
In Mindanao, which has long battled a Muslim insurgency, a handful of groups have sworn allegiance to IS.