CNS assistant chairman General Anupong Phaojinda told a press conference that key CNS members were now satisfied with the police's progress in identifying suspects and compiling evidence against them.

From evidence and reliable intelligence provided by police, Anupong could "guarantee that the three to four suspects identified were not scapegoats" and that the extended probe continued to build a stronger case against them all.

Some of the 18 suspects, including 13 military officers, are also linked with the alleged car-bomb plot to assassinate then premier Thaksin Shinawatra last year, Anupong said, even though the bomb targets appeared to be different types.

"We base everything on evidence against them, not on a logic that these men who did that thing, cannot do this thing," he said.

Anupong, as assistant Army commander tasked with overseeing the military's parallel inquiry, said police had invested considerable manpower and effort on the case - 177 investigators divided into five teams, each with its own task. "The police operations are continuing carefully with good investigation techniques, evidence-gathering, and material evidence including bomb-related devices seized," he said.

A Crime Suppression police source said one of the 19 suspects in police custody - a non-commissioned military officer - confessed to being involved in the nine bomb attacks on December 31.

A total of 18 suspects had been apprehended and interviewed by police until yesterday morning, when an Air Force non-com officer was secured. In the evening, police released a civilian who runs a chartered van service in western Bangkok's Bang Bon district for lack of evidence. Four civilians remain in police custody.

Before leaving for China on Monday, CNS chairman and Army commander Sonthi Boonyaratglin said he would hold National Police chief Kowit Watana accountable if police produced "scapegoats".