"We will start the paperwork process with the Defence Ministry on Monday, to seek their cooperation for questioning," said Police Maj-General Jate Mongkhol-hatthee, an investigator probing the alleged assassination attempt.

He did not say why police appeared to be back-tracking from the plan to arrest the officers.

Central Investigation Bureau chief Police Lt-General Montree Jamroon, the head investigator charged with solving the case, said the police would compile evidence against all four suspects.

He said no civilians were found to be involved in the plot.

Sangworn Klinchana, the wife of suspect Army Lieutenant Thawatchai, yesterday issued a third statement questioning conflicting police reports about the number of items found in the car driven by Thawatchai.

An early police statement said there were three items found in the car but they later said they found seven items. She said Thawatchai was not present when police opened the car trunk after a bomb disposal unit was called.

The suspect was asked to confirm the contents that were found were the same as what police had told the public.

The statement, jointly worked on by Thawatchai's brother-in-law Wisut Sabaithong, said the four new items were not specified by police as being found in the car.

The items were also not included in a record of Thawatchai's testimony nor in the police recommendation to the Bangkok military court asking it to refuse bail for Thawatchai.