Surayud said national police chief General Kowit Watana would be dismissed if police were found to have wrongly identified and arrested suspects in the case.

He said the decision on Kowit's future would be based on only one factor: "It's purely down to performance."

Surayud said he had not been briefed in detail by police as to why suspects in the bomb attacks were somehow also linked with those who masterminded and carried out the alleged assassination plot against ousted premier Thaksin Shinawatra.

If Council for National Security chief General Sonthi Booyaratglin pushed for Kowit's dismissal, Surayud said he still needed to discuss with the Army commander why he strongly believed that police had wrongly identified or arrested suspects.

"The DSI involvement in the case is needed to ensure fairness and counter-balancing," he added.

A Crime Suppression Division (CSD) source said a total of 18

suspects, five of whom were civilians, had been detained for questioning. Police were producing scientific evidence to further implicate them, while witness interviews, intelligence reports and tip-offs also linked them with the bomb attacks.

The source said military officers with bomb-making knowledge, who run murder-for-hire rackets and contract killings - some of whom had been involved in bomb attacks in the deep South - had been monitored as potential suspects behind the December 31 bombings.

Kowit stayed in his office at the Royal Thai Police headquarters all day and had his aides inform reporters that he had nothing to say in response to his threatened dismissal. The CNS will release a public statement on the progress of the police investigation at a news conference today.

Kowit was reportedly confronted by Surayud in a meeting and heavily criticised over reports of suspects' initial identities being leaked to the press by investigators. Surayud was reportedly upset because the leaks included highly confidential information, including investigation techniques and tip-offs volunteered by highly classified police informants and moles.

Kowit and head investigator and assistant police chief, Lt-General Phanuphong Singhara, had a 20-minute meeting. Both officers left looking tense and declined interviews.

A team of officers had a special meeting at the CSD headquarters at 6pm yesterday, but the outcome was not known at press time.

Assistant Army commander General Anupong Paojinda defended Sonthi's tough stance on Kowit's possible dismissal.

He said the Thai public could become further confused and frustrated with the CNS and its role as coup-makers if wrong suspects were publicly identified or arrested.