Southeast Asian nations plan to use spy planes and drones to stem the movement of militants across their porous borders, defence officials said at the weekend, as concerns rise over the growing clout of Islamic State in the region.

Indonesia, Malaysia and the Philippines said they will launch joint air patrols this month at their shared boundaries in the Sulu Sea, in addition to existing maritime patrols.

Authorities in the region have urged greater cooperation to counter the fallout from a raging battle with Islamic State-linked militants in the southern Philippines, the biggest warning yet that the ultra-radical group is building a base in Southeast Asia.

"Our open borders are being exploited by terrorist groups to facilitate personnel and material," Le Luong Minh, Secretary-General of the Association of Southeast Asian Nations (Asean) told the Shangri-La Dialogue, an annual regional security forum in Singapore.

The region is home to 600 million people and includes Indonesia, which has the world's highest number of Muslims. Authorities in both Indonesia and Malaysia, also Muslim-majority, have said thousands of their citizens are sympathisers of Islamic State and hundreds are believed to have travelled to Syria to join the extremist group.

Indonesian authorities blamed Islamic State for bombings last month that killed three police officers, the latest in a series of low-level attacks by the militants in the last 17 months.