Somchai Horm-laor, head of the human rights' section of the Law Society of Thailand, also questioned the charges of attempted murder that have been filed against all five military personnel. He said the "crime" was still in the preparatory stages - a crucial precondition to determine whether the suspects' acts were eligible for criminal prosecution.

"To apply the 'attempted' degree to the offence of murder in the charges against the suspects, at least a detonation device needed to have already been activated, regardless of whether the triggering worked," he said.

Commenting on the material that was publicly released on Thursday by police, who described it as a confession by Sgt-Major Chakhrit Janthara, Somchai said the Daewoo sedan that was intercepted by police and found loaded with explosives on August 24 had never travelled to nor was parked near the Air Force terminal at Don Muang airport on August 9, as caretaker premier Thaksin Shinawatra suggested earlier in a TV interview.

In the "confession statement", Chakhrit said he was waiting in a pickup truck for the Daewoo to take his place, but an Air Force military policeman asked him to leave, so the plan was postponed.

Somchai also questioned police statements that Chakhrit fled shortly before police searched his home in Suphan Buri. Somchai said police traditionally set a stakeout at a suspect's house to collect information and learn his schedule. He asked how police could raid an empty house.

The lawyer also expressed suspicion over why a foot soldier in a large-scale assassination attempt would have information about the entire plan, including the names of the people involved. "I think police are trying to extend the case to involve all parties who oppose PM Thaksin so they can use mutiny charges," he said.

Pol Maj-General Jate Mongkholhatthee, a senior investigator in charge of the case, reacted angrily yesterday when asked by reporters to comment on Chakhrit's confession, calling the people who released information from the 10-page document detailing Chakhrit's words "undisciplined".

Jate then chaired a meeting of police investigators, who were later instructed to compile more evidence against Maj-General Phairoj Theerapharb. Phairoj was not included in Chakhrit's claims and so was granted a temporary release on bail by the Bangkok military court on Thursday.

A team of police seized a computer belonging to Colonel Suraphol Supradit, one of the five military suspects, from his office at the Internal Security Operations Command to retrieve some information on it that they said they believed could reveal more evidence.

Police said they had arranged a re-enactment for today. Four suspects are expected to demonstrate their actions in regard to the alleged car-bomb plot.

A police source said some of Thaksin's personal security guards had confirmed that Chakhrit was near Bang Phlat intersection on August 24. That is where the Daewoo was intercepted by police, contrary to Chakhrit's statement earlier that he was not at the scene on that day.

A military source said Colonel Supaphol Supradit, another of the five suspects, had a personal business operating commuter van services in Pathum Thani. The source said he had close ties to a national-level politician based in the Northeast who was close to the country's leader and was instrumental in organising several pro-government demonstrations.

Royal Thai Air Force commander ACM Chalit Phukphasuk said security at the Air Force terminal would be normal today when Thaksin departed for Finland to attend the Asia-Europe meeting.

Thaksin met yesterday with the commander of the Cavalry Division, Maj-General Sanit Phrommas, the caretaker prime minister's classmate from Class 10 from the Armed Forces Academy Preparatory School. The two men held a secret 30-minute meeting after leaving Government House.

Thaksin later went to play golf at a driving range in the Wang Thong Lang area, where he was briefed on the progress in solving the car-bomb case by Central Investigation Bureau chief Pol Lt-General Montree Jamroon, who is leading the investigation.