But interrogations of Singapore's latest terror detainee, Rijal Yadri Jumari, surfaced intelligence that a group of foreign Jemaah Islamiah (JI) elements are actively trying to revive the clandestine grouping.

Internal Security Department (ISD) investigations and questioning of more than 50 JI detainees at the Whitley Road Detention Centre in the past seven years have 'led to critical breaks in Singapore's counter-terrorism efforts', said the Ministry of Home Affairs (MHA).

The information obtained has also helped cripple a terror network that operated in the region and beyond.

MHA said being able to question detainees as and when new intelligence comes has been 'operationally advantageous', and helped identify several lethal terrorists.

One ISD detainee identified Amrozi, who plotted the 2002 Bali blasts which killed 200 people, based on a description provided.

'Based on this lead, the Indonesian authorities identified and later apprehended Amrozi and many others...including (his brother) Mukhlas,' said MHA.

Both Amrozi and Mukhlas, who had directed the Singapore JI, were found guilty of the Bali blasts and are awaiting execution in Indonesia.

Detainees also gave information which 'considerably' aided investigations, and revealed the JI's operational plans aimed at causing massive damage in Singapore.

That was not all.

The ISD shared intelligence on the regional JI network covering Indonesia, Malaysia, southern Philippines and Australia with security agencies in those countries.

Those agencies then disrupted cells in their countries.

In Malaysia, many JI members were detained and JI madrasahs in Ulu Tiram in Johor and Kelantan were shut.

The JI's Australian network in Perth, Melbourne and Sydney was also disrupted.

In Singapore, the JI had been discussing potential targets since the mid-1990s, and preparations intensified after the Sept 11, 2001 terror attacks on the United States.

Targets included embassies, Changi Airport, MRT stations, water pipelines and the Ministries of Defence and Education - and these were 'the more developed plans'.

ISD investigations saw key members of the local JI network apprehended - including spiritual leader Ibrahim Maidin and experienced operations planners Mohamed Khalim Jaffar, Hashim Abas and Ja'afar Mistooki.

In the first phase of operations in December 2001, 13 JI members and two Moro Islamic Liberation Front (MILF) members were rounded up.

Resulting investigations surfaced many others, and in August 2002, another 21 men were arrested, with 18 placed under detention orders.

Many more were warned or placed on restriction orders which limited their activities.

About half the detainees have now been released after they were assessed to have been rehabilitated, said MHA.

ISD interrogations also managed to identify and track down Singaporean JI members who had fled overseas.

Working with foreign partners, ISD found and brought back 10 such men in the past five years.

MHA described these arrests as 'significant'.

Arifin Ali, who was arrested in May 2003, worked with a few Thai extremists and was planning to bomb several embassies - Singapore's included - in Bangkok.

Known also as John Wong Ah Hung, he had been considering targeting Singapore's ambassador to Thailand (who was then Mr Chan Heng Wing) but his plans were foiled by his timely arrest.

Others arrested abroad include Anis Mohd Mansor in 2004; and Mas Selamat Kastari, Mohd Rashid Zainal Abidin and Ishak Mohamed Noohu, in 2006.

The latter three were involved in Mas Selamat's plan to crash a plane into Changi Airport. Their interrogation revealed new information that the group had continued to plan such an attack even after their first attempt was thwarted, said MHA.

Early last year, four others were brought back: Mohd Hussain Saynudin, Mohd Yassin Mohd Noor, Jamil Ansani and Ibrahim Mohd Noor. Three were detained and Jamil was given a restriction order limiting his movements.

MHA added that interrogation of these detainees hiding overseas turned up names of many foreign JI members and collaborators, which ISD shared with its security partners.

Such intelligence exchange is critical because terror groups do not respect national borders, noted security expert Kumar Ramakrishna.

But terror outfits also want to know if they have been penetrated, monitored or compromised, so agencies are careful to ensure they do not 'tip off the bad guys' as to just how much is known, he added.

Intelligence and security officers from several countries have interviewed some detainees in Singapore, said MHA.

Several detainees also agreed to testify via video conference at foreign terrorism trials, MHA added.

Among them was Faiz Bafana, released in 2006, who testified at the closed-door hearing of Zacarias Moussaoui in a Virginia federal court in 2002.

Moussaoui was convicted of conspiring with the Sept 11, 2001 hijackers and has been sentenced to life without parole in the US.

Bafana, Hashim Abas and Ja'afar Mistooki also testified at the 2003 trial of JI leader Abu Bakar Bashir in Jakarta.

The trio testified to Bashir's involvement in JI, 'even when Indonesian JI members were too afraid to do so', said MHA.

International Crisis Group analyst Sidney Jones said the willingness of security agencies in the region to cooperate has increased dramatically in recent years, but some still needed to beef up skill levels.

zakirh@sph.com.sg