TARAKAN (NORTH KALIMANTAN) - Indonesia is on alert against militants disguising as refugees from Marawi city, which remains under siege by hundreds of fighters from the Maute and Abu Sayyaf terrorist groups in southern Philippines.
Clashes in the city between the Philippine armed forces and militants, including many foreign fighters from Indonesia, Malaysia and elsewhere in the region who are loyal to the Islamic State in Iraq and Syria (ISIS), have continued into their fourth week.
Analysts have warned of militants hiding among the 200,000 displaced residents of Marawi, many of whom have become refugees as the extremists tear apart their hometown in a bid to create the next wilayah, or state of ISIS in South-east Asia.
"We need to be alert, out of 500 to 600 terrorists there, 257 have been killed but the remainder, according to information we received, have been leaving the conflict areas with the refugees," said Indonesian armed forces (TNI) chief Gatot Nurmantyo on Monday (June 19).
The four-star general was speaking to reporters on-board the warship KRI Suharso following the launch of joint maritime operations by Indonesia, Malaysia and the Philippines to fight terrorism and transnational crimes in the Sulu Sea earlier in Tarakan island, North Kalimantan.
General Gatot said the TNI is committed to an "all out effort" to beef up security in the Sulu Sea and waters surrounding the area, and it has already deployed Sukhoi fighter jets, Boeing spy planes for aerial surveillance, as well as warships and submarines to prevent incursions by militants being flushed out from Marawi.
Philippine armed forces spokesman Brigadier-General Restituto Padilla, told reporters during a briefing in Manila that "hopefully, we can address, with these patrols, movements of threats across our porous borders".
"We can have more organised patrols to prevent abductions," he added. "More than that, we can prevent movements of personnel bound from one country to another who are fugitives of their own lands and seeking havens, and wanting to provide assistance to groups of jihadists."
Additional reporting by Raul Dancel in Manila.