JI bomb-maker linked to southern militants

Militants in the South are believed to be receiving training in bomb-making from the notorious Jemaah Islamiyah terrorist group active in Indonesia, a security source says.

Khunying Porntip urges authorities to keep an eye on the new form of attacks

The source said a key member of JI believed to be linked to the July 17 bombings of the JW Marriott and Ritz-Carlton hotels in Jakarta was providing the southern militants with the bomb-making training.

He also said radios, rather than mobile phones, were being used to detonate bombs - a method devised to avoid detection by authorities' efforts to track phone signals.

Southern insurgents have embraced transceiver technology in their bomb attacks, a technique found to be common in the Iraq war.

Radio transceivers are known to have triggered recent bombings in the far South. They make for a more efficient trigger device than mobile phones because authorities cannot interfere with the signals.

A bomb attack in Yala's Yaha district on July 17, which killed two soldiers and wounded five people, is believed to have been detonated by a transceiver, said Khunying Porntip Rojanasunan, director of the Central Institute of Forensic Science.

The insurgents have also produced home-made grenades which they hurl into crowds.

One bizarre device they have invented is a fake boundary marker stuffed with explosives which mostly targets authorities on patrol duty.

Khunying Porntip said the militants usually destroy the real markers and replace them with fakes. The bomb inside is triggered by a mobile phone or is wired to a timer.

She said authorities should coordinate intelligence information and keep abreast of new forms of attacks.

Col Tawisak Jantrasin, head of the army's explosive ordnance disposal unit, said the use of transceivers to launch attacks was not new. It has been absent from the attack scenes for a long time. But the Yaha assault confirmed the device had made a comeback and this time the transceiver-detonated explosion had been a lot harder to foil.

A bomb expert in the far South, who requested anonymity, believed the transceiver operates with a ''dual tone multi-frequency'', the same communication frequency used by bombers in Iraq and Afghanistan.

Transceivers are more efficient than mobile phones as they can be used from a far greater distance and their signals cannot be cut by authorities.

An investigation into the Yaha case found the attacker keyed in a code in his transceiver to detonate the bombs, which were hidden in two cooking gas cylinders weighing about 15 kilogrammes.

The cylinders were placed in a pickup truck, he said.

A single transceiver could also detonate many bombs at the same time, the source said.

Security forces are wary of being lured to a blast scene and walking into a trap in which insurgents trigger a second bomb.

Explosive-stuffed fake boundary markers are often secondary bombs.

Col Tawisak has told security personnel to be vigilant, although there have been fewer bomb attacks this year compared with last year.