The Indonesian authorities have started to isolate radical ideologues Aman Abdurrahman, Abu Bakar Bashir and three other terrorist inmates, in a bid to curb their influence beyond the prison walls.
Their visitation rights on Nusakambangan prison island in Java have also been tightened, with only immediate family allowed.
The move follows investigations which show Aman may have ordered the Jan 14 attacks in Jakarta that left eight people dead, including the four attackers.
It was also found that Aman, 44, had cellphones and SIM cards smuggled into his cell between October 2014 and last February. Police are still checking whether he used those phones to orchestrate the hit.
Inmates placed in isolation are allowed to have visitors twice a week, as stipulated by law, but they will no longer be allowed physical contact. Visits will be held in rooms divided by a glass partition, a government official told The Straits Times yesterday, and Aman, Bashir and the three others - militants Heri Kuncoro, Iwan Darmawan Muntho, alias Rois, and Abrory, alias Makadov - can no longer receive packages from visitors.
Heri is in jail for smuggling firearms into Indonesia from the Philippines, while Rois is on death row for his role in the 2004 Australian embassy bombing.
Abrory, who was head of a radical Islamic boarding school in Bima, West Nusa Tenggara, had influenced his students to make bombs.
Aman has been moved from a 5m-by-15m cell he shared with four other terrorist inmates in Kembang Kuning prison to an isolation cell in the Pasir Putih penitentiary, also on Nusakambangan.
"We are doing it gradually. More inmates will be moved to the isolation block," the government official, who spoke on condition of anonymity, told The Straits Times.
Bashir, 77, and his cellmate Heri have been moved from the island's Batu penitentiary.
Aman and Bashir were convicted for their respective roles in helping to set up a paramilitary training camp in Aceh that police raided in early 2010. They each occupy a 2m-by-3m cell. The block has more than a dozen separate units which prevent occupants from communicating with each other.
"We only open their doors for meals and they are constantly monitored by security cameras," Mr Eka Putra, a warden at the Pasir Putih penitentiary, which houses the isolation block, told The Jakarta Post.
Abdul Rochim Bashir, a son of Bashir, condemned the government's move to put his father in an isolation cell, saying the conditions there are not proper, Islamic website Panjimas.com reported.
"If my father is deemed as an ideologue, then it is the fault of the prison management that failed to carry out a deradicalisation programme, therefore the punishment should not be given to Bashir," he was quoted as saying. In the isolation cell, his father would be barred from conducting the weekly Friday prayer, the younger Bashir said.
"Dealing with terrorism should not breach anyone's rights, let alone the right to carry out a prayer. If one's right to do a prayer is denied, that is equivalent to a form of terrorism," he added.