The Indonesian prison system is a fertile recruiting ground for terrorist organizations to find new recruits, a former jihadist said on Wednesday.

"By going to several jails, I have direct experience of seeing that terrorists continue to recruit new members that they met and trained in jail," Abdul Rahman Ayub, a former member of Jemaah Islamiyah, said in Mataram, West Nusa Tenggara, as quoted by the state-run Antara news agency. "That is why the number of terrorists continues to rise."

Ayub said that many incipient terrorists were radicalized in jail, where many had arrived to serve sentences for minor crimes.

"In the past, the recruitment pattern started with bai'at [a special ceremony to receive new members], but it's not necessary now," Ayub said. "Mostly the prisoners invited are those who are frustrated by the authorities."

The prison's Koranic study group was frequently used to recruit new jihadists, Ayub said.