Former education minister Chaturon Chaisang yesterday rejected an additional charge put against him of filing information into a computer system that could harm security.
He appeared at a court martial on a charge of resisting martial law imposed by the military junta.
Prosecutors asked the court to allow Chaturon to be held for a further 12 days as investigation and interrogation proceedings have not yet been completed.
Chaturon has been free on bail since June 6 after his initial arrest, but prosecutors want him back in custody to allow them to prepare more evidence before trial.
Prosecutors yesterday added an additional charge of computer crime against him for putting information they claim could have harmed harm security into a computer system. He could be sentenced for up to five years if proven guilty.
Chaturon told the court that he rejected the additional charge on the grounds that prosecutors applied it to him hastily and did not give him any chance to defend himself, said his lawyer Narinphong Chinapak.
The prosecutors should have given the former minister notice in advance that they wanted to press an additional charge, said the lawyer.
Chaturon was arrested on May 28 after he defied an order of the National Council for Peace and Order to report to the junta. He also faces charges of instigating unrest.
He will next appear in court on July 2.