By Girish Gupta

CARACAS, July 6 (Reuters) - At least 123 members of Venezuela's armed forces have been detained since anti-government unrest began in April on charges ranging from treason and rebellion to theft and desertion, according to military documents seen by Reuters.

The list of detainees, which includes officers as well as servicemen from the lower ranks of the army, navy, air force and National Guard, provided the clearest picture to date of dissatisfaction and dissent within Venezuela's roughly 150,000-strong military.

The records, detailing prisoners held in three Venezuelan jails, showed that since April nearly 30 members of the military have been detained for deserting or abandoning their post and almost 40 for rebellion, treason, or insubordination.

Most of the remaining military prisoners were charged with theft.

Millions of Venezuelans are suffering from food shortages and soaring inflation caused by a severe economic crisis. Even within the armed forces, salaries start at the minimum wage, equivalent to around $12.50 a month at the black market exchange rate, and privately some members admit to being poorly paid and underfed.

Since the opposition started its protests more than three months ago, a handful of security officials have gone public with their discontent. Last week, rogue policeman and action movie star Oscar Perez commandeered a helicopter and attacked government buildings, claiming that a faction within the armed forces was opposed to Maduro's government.

The military documents seen by Reuters, which covered detentions until mid-June, appeared to support opposition leaders' assertions that anger and dissent among soldiers over economic hardship is more widespread.

"This shows low morale and discontent and, of course, economic necessity," one former army general said of the detentions, asking not to be named for fear of reprisals.

Venezuela's military and Information Ministry did not respond to requests for comment.

Venezuelans view the armed forces as the key power broker in their country. Opposition leaders have repeatedly exhorted military leaders to break with socialist President Nicolas Maduro.

Maduro has said that he is the victim of an "armed insurrection" by U.S.-backed opponents seeking to gain control of the OPEC country's oil wealth. He has said that the top military brass have been standing by him.

The National Guard has been at the forefront of policing protests across the country. It uses tear gas, water cannons, and rubber bullets against masked youths who in turn hurl stones, Molotov cocktails and excrement at security lines. At least 90 people have been killed since April.

Privately, some National Guard members on the streets have acknowledged being exhausted, impoverished and hungry, though most remain impassive during protests and avoid engaging in conversation with reporters.

"LITTLE RAMBOS"

The documents, which identified detainees by their rank, listed captains, sergeants, lieutenants and regular troops held in three prisons in different parts of Venezuela.

Ninety-one are at Ramo Verde, a hilltop jail near Caracas where opposition leader Leopoldo Lopez is also held.

Another two dozen are at Pica prison in the northeastern city of Maturin and eight are at Santa Ana jail in the western state of Tachira, near the Colombian border.

It was not immediately clear if military prisoners were also being held in other jails.

Three lieutenants fled to Colombia and requested asylum in May, and a man who said he was a Venezuelan naval sergeant appeared in a video published by local media last month expressing his dissent and urging colleagues to disobey "abusive" and "corrupt" superiors.

Maduro has blamed the problems on an "economic war" being waged by the opposition with backing from Washington, a position taken in public by senior military officials.

"Many are seeking ... little 'Rambos' in the armed forces, but you're not going to find them," Defense Minister Vladimir Padrino said in a video published on Monday, alluding to speculation of a military coup.

Perez, who staged the helicopter attack last week against the Interior Ministry and the Supreme Court in Caracas, appeared in an online video on Wednesday vowing to keep up the fight.

"We are fully sure of what we are doing and if we must give up our lives, we will hand them over to the people," Perez said, sitting in front of a Venezuelan flag and rifle. (Editing by Alexandra Ulmer, Andrew Cawthorne, Toni Reinhold)