DSI agents are compiling information on two men and a woman who were filmed by surveillance cameras at CentralWorld, one of the nine sites bombed. One of the men could be a civilian with a criminal record and history of involvement with insurgent activities in the South, Sunai said.

He said images of the two other suspects were undergoing a visual enhancement process at an overseas lab, so that they could be identified or checked against criminal records. The security-camera footage shows the three people approaching a dustbin and dropping something in before fading away.

Sunai said everything would become clearer in the near future, but whether the information could be made public was another matter. He did not say how soon the masterminds of the bomb attacks or other operatives would be identified. "How can the country go on and survive if we keep failing to find the culprits? The time is needed because we don't want to make any mistakes or do anything without evidence that might affect civil liberties or result in legal disadvantage [during trials]," he added.

Sunai said the images were from the same security-camera footage examined by the police, who did not report finding any evidence from it.

He said the DSI had interviewed different witnesses from the police and had not found any links between the bombings and the 19 suspects, including 15 military officers, who were detained by the police for a week before being released last Friday.

Meanwhile, police investigators who have been ordered to start re-examining the case are aiming their enquiry at people with connections to insurgents in the South, according to a police source.

The source said a man caught on surveillance cameras dropping a potato-chip cylinder in a trash bin at the Seacon Square department store was possibly a suspect wanted by police in Yala's Betong district. The source said the man had been identified, but it was not confirmed if he was the same person named in the Betong police arrest warrant. He added that the man was involved with a separatist movement identified as "PYNSS", but mostly carried out attacks for money.

Council for National Security chairman General Sonthi Boonyaratglin yesterday sympathised with national police chief Kowit Watana, saying that his former classmate had served mainly with the Border Patrol Headquarters and might not have sufficient skill in investigations.

Asked about Prime Minister Surayud Chulanont's earlier statement that the final decision to dismiss Kowit rested only with Sonthi, the Army commander merely smiled and shook his head as a refusal to comment.