If found guilty the accused soldiers "face up to 30 years prison," defense attorney for the suspects Alonso Medina told AFP.

All nine -- six lieutenant colonels, a first lieutenant and two sergeants, one of them a woman -- were ordered sent to prison in a hearing that ended early Saturday, Medina said.

"No concrete evidence against the officers was presented, only testimony based on alleged intelligence reports," the lawyer said.

Two of those detained are battalion commanders -- one in Caracas, and the other in San Cristobal, on the border with Colombia.

The soldiers were taken into custody by military counter-intelligence agents on March 2, accused of belonging to an anti-Maduro movement known as the "Movement of Transition towards the Dignity of the People," Medina said.

The arrests come more than a week after Maduro ordered 24 retired and active duty military officers demoted and kicked out of the service.

Among them was Raul Baduel, a minister of defense under Maduro's predecessor, the late Hugo Chavez.

The arrests are being carried out as a way "to keep the military institution submissive and loyal" to the government's so-called Bolivarian Revolution, said Rocio San Miguel, an expert on military affairs.

"The biggest danger that Maduro faces comes from his generals and admirals," San Miguel told AFP. "And since he can't act against them, he picks on the mid-level officers to see how they react."

Analysts believe that the military's support is key to Maduro maintaining power amid a worsening crisis that has driven hundreds of thousands of Venezuela to try to flee the country.

Maduro is seeking a second six-year term in elections set for May 20 that most of the main opposition parties are boycotting.