In its latest effort to reach out to supporters in South-east Asia, the Islamic State in Iraq and Syria (ISIS) has posted photos and a video of Malay-speaking children training with weapons.

The footage depicts a group of at least 20 boys studying, praying, eating and undergoing defence and weapons lessons in territory held by the terrorist group.

It comes amid warnings by experts that ISIS is beefing up its external operations wing and courting further support in the region.

"There has been a surge in Indonesian- and Malay-language material posted by ISIS online," Mr Jasminder Singh, a research analyst at the S. Rajaratnam School of International Studies, told The Straits Times.

"There have been previous videos featuring Arab and Central Asian children, and it is clear they are now reaching out to target supporters in South-east Asia."

Titled Education In The Caliphate, the video was posted over the weekend by the Malay- language media division of ISIS, as a teaser for a longer piece to be posted later.

Also uploaded are "exclusive" photos of students at the Abdullah Azzam academy, which uses Malay as a medium of instruction and was set up for the children of South-east Asian fighters.

Abdullah Azzam was a radical ideologue who mentored Al-Qaeda leader Osama bin Laden.

Analysts say the school indicates that ISIS' Malay Archipelago Unit, set up last year and called Katibah Nusantara, has grown. The decision to say the school teaches in Bahasa Melayu, rather than Bahasa Indonesia, suggests a defiance of the boundaries of the nation state.

The video is also the first to show children from this region being trained for active combat. An estimated 500 fighters from the region, including southern Thailand, have joined ISIS.

"They want to seek financial support, and to attract Indonesians and Malaysians to migrate to the caliphate," said analyst Robi Sugara of research outfit Barometer Institute.

The video comes as Turkey said last week it had detained 16 Indonesians trying to cross into Syria, and two weeks after Malaysian police identified two Malaysians in a beheading video.

This month, Deputy Prime Minister Teo Chee Hean told Parliament that returning fighters posed a danger to the region, and self-radicalised individuals may also be influenced by ISIS to carry out attacks in their home countries.

The two-minute video features Indonesian Katibah member Bahrumsyah, who left for Syria last May. Its message is that these children will "finish all oppressors, disbelievers, apostates", and ends with a child firing a revolver.

Mr Abdul Halim Kader of Muslim group Taman Bacaan said there is a fear that some young people might be influenced by such videos, and educators had to do more to counter their message.

Said Mr Singh: "The message they aim to send is, 'These children will be the next generation of fighters. You can capture us, kill us, we will regenerate, no matter how hard you try.' "

zakirh@sph.com.sg