The looming release of hundreds of militants from Indonesia's prisons, hotbeds of radicalism where influential Islamists openly preach extremist ideology, is ringing alarm bells and raising fears some will join forces with the Islamic State group.
More than a decade after Indonesia vowed to dismantle terrorist networks to stem a series of attacks, neglect of jails has allowed top detainees to promote their views behind bars, and even beyond thanks to smartphones and laptops.
About 200 convicted militants are due for release in the next two years, and experts say inadequate deradicalisation efforts mean many will leave jail with their ideology intact.
"Prisons are still the epicentre of terrorism in Indonesia. The most dangerous militants are behind bars and recruitment is going on," said terrorism expert Taufik Andrie from the Jakarta-based Institute for International Peace Building.
The alarming trend in the world's most populous Muslim-majority country comes despite authorities' growing concern about Islamic militancy and in particular Islamic State (IS), which has declared an "Islamic caliphate" across swathes of Syria and Iraq.
Authorities say about 60 Indonesians are believed to have joined IS, although most analysts believe the true figure is up to 200, and concerns are mounting that they could return and revive sophisticated militant networks.
Singapore has said that IS jihadists from Malaysia and Indonesia have formed their own group -- Katibah Nusantara Lid Daulah Islamiyyah, or Malay Archipelago Unit for the Islamic State which poses a clear security threat to Southeast Asia.
Indonesia began a long clampdown on extremists following the 2002 Bali bombings that killed 202 people on the resort island, mostly foreigners. That attack and others were blamed on the Al-Qaeda-linked Jemaah Islamiyah (JI), which has since been severely weakened.
