Police can only charge Lieutenant Thawat-chai Klinchana with unlawful possession of explosive devices at this point, while his elder brother yesterday said Thawatchai was an admirer of the prime minister and had always spoken out against the anti-Thaksin movement.

Police spokesman Lt-General Ajiravid Subarnbhesaj said Thawat-chai would be facing just one charge of unlawful possession of explosives for the time being.

"By law, preparing to do something is not yet an offence," he said. However, he said the investigation was ongoing and, if progress was made, further details would be made public. The suspect's elder brother, Staff Sergeant Ittipon Klin-chana, said Thawatchai used to like the premier a lot and was always against the anti-Thaksin movement.

"He disagrees with people who are against Thaksin. How can he ever try to assassinate the premier then?" Ittipon said, after he was allowed to meet his brother for five minutes.

Four days after Thawatchai was arrested in a Daewoo car loaded with explosive devices not far from the prime minister's residence, an investigation into the alleged assassination plot was still crawling at a snail's pace. His arrest has heightened political tension in the country. Thawatchai has maintained his innocence while various sources gave differing accounts of what exactly happened on Thursday.

Police yesterday said they did not plan to issue summonses for any more suspects at this point, even though security sources disclosed that there were at least four senior military officers involved in the foiled plot to assassinate Thaksin.

 During their brief meeting yesterday, Ittipon said Thawatchai told him that a friend asked him to fetch a Daewoo car and he was arrested even before he had turned on the car engine. Thawatchai reiterated that he was unaware the vehicle contained a large amount of explosives.

"I believe this is 90 per cent of the truth," Ittipon said. He complained that the meeting was so short that Thawatchai was unable to tell him all the details.

Since his arrest on Thursday, Thawatchai has been detained at the Crime Suppression Division.

In his detention cell, there were two police commando officers. In front, three other commando officers stayed on guard. Thawatchai was not allowed any food other than what was prepared by the police.

He was apparently stressed.

At around 3pm, Thawatchai was taken out of the detention cell to be questioned by police investigators. The session lasted more than two hours.

When he was taken back to his cell, his wife and relatives brought a lawyer to meet him.

The lawyer, who spoke on condition of anonymity, said Thawatchai had already signed documents appointing a team of three lawyers to represent him.

"From now on, we will be present when police question him," the lawyer said.

He said a bail request for Thawatchai's temporary release would be filed with the military court and assets worth more than Bt1 million would be submitted as a bond.

Police allowed Thawatchai to meet his wife and lawyer for less than 10 minutes.

"He has the constitutional right to get bail. Also, he needs regular treatment for his hyperthyroid," the lawyer added. Thawatchai's wife declined to give any interviews.

Investigators yesterday summoned Thaksin's security people, bomb-disposal officials and officers from the Crime Scientific Detection Division involved in the case to testify and submit fingerprints.

A police source disclosed that the investigators planned to match their fingerprints on objects seized from the scene so as to identify fingerprints not belonging to the officials. "The remaining fingerprints will point to persons who are involved in the plot," the source said.

Investigators had also closely examined video clips featuring what happened on Thursday, which had been filmed by Thaksin's security people.

"The clips featured crowds of people around the scene too. It is possible that some other suspects were among those captured in these clips," the source said. 

The source also disclosed that the Daewoo vehicle, which was seized from the scene, was bought on a hire-purchase contract and its owner had defaulted and absconded.

"Investigators are going after the owner," the source said.

Another police source said the investigators were keeping a close watch on two military sergeants who were close to Thawatchai and had extensive knowledge about bomb-making.

Meanwhile, Thaksin yesterday left his residence with stepped-up security measures. His destination was kept a secret.

However, it was later found that Thaksin visited a member-only golf course to play with Suriya Jungrungreangkit and Pongsak Ruktapongpisal. While the premier was there, all vehicles going in and out of the golf course were checked.