Indonesian prisons may be a fertile recruiting and training ground for Al Qaeda-linked militants, blamed for a string of bomb attacks in recent years, because jailers are too soft on them, an international think-tank said on Tuesday. Indonesian militants are finding it harder to recruit new bombers, but arresting top leaders may prove futile in eradicating them, the International Crisis Group (ICG) said. The practice of "recycling" militants means authorities need to focus on what happens in prison, and what becomes of the families of militants, if they want to tackle terrorism, it said. "The government needs to ensure that prisons do not become a place where radicalisation increases or is reinforced," the Brussels-based group said in a 57-page report. Indonesia, the world's most populous Muslim nation, has jailed more than 30 militants convicted of the 2002 Bali bombings, blamed on the regional Jemaah Islamiah (JI) network. They have been handed sentences ranging from a few years to the death penalty for the nightclub attacks that killed 202 people, many of them foreign tourists.