The Ansor youth group -- affiliated to the country's largest Muslim organization, the 60-million-strong Nahdlatul Ulama (NU) -- said the unit had more than 200 members, some of whom were trained in bomb disposal.

Group chairman Nurson Wahid told the AFP that members of the unit, known as Detachment 99 in a nod to the country's counter-terrorism Detachment 88 squad, were also trained in preventing people from adopting extremism.

"Detachment 99 will not intervene... in law enforcement, launching raids on terrorists or arrests," he said.

Wahid said that the group will train more people and then deploy them to 17 regions considered to be vulnerable to extremist teachings, including several cities on the island of Java.

AFP