The weekend arrest and interrogation of leading Muslim militant chief Jafar Umar Thalib follows a week of allegations that his group, Laskar Jihad, was behind an attack on a Christian village in Ambon which left 14 people dead.
It also comes a year after his last arrest and release, despite many witness reports of the active involvement of Laskar Jihad in religious fighting in both the Malukus and Central Sulawesi.
Police said Thalib was arrested in the East Java capital of Surabaya and had been flown to Jakarta for questioning and detention.
'He has violated the law - he has been preaching and insulting the Government and has provoked Muslims and asked them to prepare bombs,' said police spokesman Saleh Saaf.
Thalib is accused of delivering a provocative speech two days before the Ambon attack on April 28, in which he denounced the government-brokered Malino peace accord for the Malukus and called for Muslims to fight on.
Thalib is a controversial figure, not only because he leads a trained and armed fighting force which is trying to penetrate other largely Christian areas of Indonesia such as Papua (formerly Irian Jaya). He is also believed by analysts to receive some of his funding and encouragement from figures within the Indonesian military.
Some US media reports allege that he is linked to the international al-Qaeda network.