Lt-Colonel Manas Sukprasert is escorted from his unit in Lop Buri to the Crime Suppression Division in Bangkok yesterday where he was charged with attempted murder along with three other Army officers.

Police yesterday charged four Army officers with the attempted murder of Prime Minister Thaksin Shin-awatra. One lieutenant colonel was taken into custody.

The charges relate to the alleged attempt on Thaksin's life late last month.

The four officers identified yesterday morning are Maj-General Phairoj Theerapharb, Colonel Suraphol Supradit, Lt-Colonel Manas Sukprasert and Sgt-Major Chakhrit Janthara.

Lt Thawatchai Klinchana - who has already been charged with illegal possession of explosives - now faces additional charges of attempting to murder Thaksin, an on-duty official; attempted murder of others; criminal conspiracy and forging and using official documents.

He has denied all five offences.

A team of police investigators apprehended Manas yesterday evening at Erawan Camp, home to the Army Special Operations Command. Police and military officials reached an agreement for him to be handed over to police.

Police have requested the other three officers present themselves at the Crime Suppression Division at 10am on Thursday.

There they will be asked to formally acknowledge the charges. If they fail to appear, arrest warrants will be sought.

All five officers are assigned to the Internal Security Operations Command (Isoc) and reportedly have close ties with Isoc deputy director General Pallop Pinmanee. Pallop was dismissed immediately after Thawatchai was arrested.

Thawatchai is an Isoc staff member who has been in custody since the alleged plot was foiled nearly two weeks ago. Police discovered him with a car loaded with explosives near caretaker Prime Minister Thaksin Shinawatra's Bang Phlat residence on August 24.

Police have not revealed evidence against Manas or the three others.

Neither did investigators provide details of the roles played by each of the suspects despite verified reports clearly indicating that all officers played different roles in the alleged plot.

Chakhrit is reportedly accused of "identifying the target" and obtaining the Daewoo sedan purchased by Suraphol.

Manas was reportedly responsible for obtaining explosives.

Phairoj is alleged to have coordinated between team members and others that may have masterminded the plot.

Police are waiting for the results of examinations of electronic circuits found at the Suphan Buri home of Manas in a raid last Saturday. The tests will determine if the circuits were similar to those found with explosives in the Daewoo sedan occupied by Thawatchai.

Phairoj was described as an Army expert assigned to Isoc. He said yesterday he was not a flight risk and was waiting to receive orders from superiors to present himself to the police.

He admitted knowing three of the officers charged. He had seen Thawatchai, but never spoken to him.

Police Central Investigation Bureau commander Lt-General Montree Jamroon said the request for the officers to present themselves voluntarily was made to comply with Defence Ministry regulations that stipulated arrest warrants be issued only when suspects failed to cooperate.

A lawyer for Thawatchai, Nithikorn Nonthasawas, said an application would be made for his client's release after his first 12-day detention period expires today.

Nithikorn complained about police releasing a video-disc with an apology by Thawatchai for driving the car. He said the video violated his client's rights.

"He has become a defendant in a more serious crime in the eyes of the public when the only charge against him was being in illegal possession of explosives," the lawyer said.