Caracas (AFP) – A top deputy to opposition leader Juan Guaido was jailed Friday at a military prison in Caracas following his dramatic arrest, ratcheting up tensions in Venezuela ahead of fresh protests Saturday against the government of President Nicolas Maduro.

Edgar Zambrano, the deputy speaker of the opposition-majority National Assembly, is being held in preventive detention for “the flagrant commission of the crimes of treason, conspiracy and civil rebellion,” the Supreme Court said in a statement announcing the verdict of a lower court.

Zambrano was arrested by Maduro’s Sebin intelligence service in dramatic circumstances Wednesday for supporting a failed April 30 uprising organized by Guaido.

Zambrano was transferred to the headquarters of the military police in Caracas’ largest military complex, Fort Tiuna, the court said.

The lawmaker is one of 10 charged by the Supreme Court for participating in the failed uprising, the latest push by the US-backed Guaido to undermine Armed Forces support for the embattled Maduro.

Three of the lawmakers — Richard Blanco, Mariela Magallanes and Americo De Grazia — have sought refuge in the Argentine and Italian embassies in Caracas. 

Zambrano’s lawyer Lilia Camejo denounced the procedure under which Zambrano, a civilian, was sent to a military prison, and said his rights had been violated.

“From the moment of the arrest, they have violated the deputy’s rights. We did not have access to the file, nor could we be appointed in his defense,” Camejo told reporters.

Guaido said on Thursday the arrests were part of a bid by Maduro to dismantle the National Assembly legislature, Venezuela’s sole opposition-controlled institution.

“If we can talk about a coup d’etat in Venezuela, here it is: the dismantling of the national parliament,” Guaido told a news conference, accusing Maduro’s regime of “state terrorism.”

The uptick in regime repression “may be a precursor” to targeting Guaido himself, said Latin American analyst Risa Grais-Targow of Eurasia Group. “Zambrano’s arrest may be a test to gauge the response of the international community before it moves against Guaido.”

His arrest on Wednesday night was both bizarre and dramatic, with the lawmaker commenting on events live on Twitter as they unfolded.

The 64-year-old’s car was surrounded outside his Democratic Action Party’s headquarters before it was towed, with him still in it, to the notorious Helicoide prison inside Sebin headquarters.

Guaido led around 30 members of the armed forces in trying to spark an insurrection to dislodge Maduro on April 30, but it quickly fizzled out after two days of deadly clashes.

The 35-year-old called for a national demonstration on Saturday to reject measures taken by the Supreme Court against opposition lawmakers.

– Turmoil –

Venezuela was plunged into turmoil in January when Guaido declared himself acting president in a direct challenge to Maduro’s authority.

He has since been recognized by more than 50 countries as he steps up the pressure to oust Maduro, whom he considers illegitimate after 2018 elections widely seen as fraudulent.

But through months of crisis, Maduro — supported by China, Russia and his armed forces — has stood firm.

“The existing external and internal pressures have not been enough to convince Maduro and his inner circle to negotiate their exit ramp. What happens next in Venezuela is highly uncertain,” said Moises Rendon of the International Crisis Group.

Separately on Friday, Venezuela announced it was re-opening its land border with Brazil after Maduro ordered it shut in February, frustrating Guaido’s attempt to bring stockpiled mostly-US humanitarian aid across the border.

Vice President Tareck El Aissami said the frontier with Brazil was “once again restored” adding that maritime links with the Caribbean island of Aruba were also reopened.

However, the border with Colombia and links with the Dutch Antilles — closed at the same time on Maduro’s orders — will remain closed, El Aissami said.

In February, Guaido defied a Supreme Court travel ban to orchestrate aid deliveries from the Colombian side of the border. Despite rioting in border towns, a blockade by Venezuela’s Armed Forces endured.

Maduro had dismissed the delivery of humanitarian aid as pretext for a US incursion, before last month accepting the first of a series of aid deliveries organized by the Red Cross.

Venezuela has suffered more than four years of recession marked by shortages of basic necessities such as food and medicine.

The United Nations says a quarter of its 30 million population is in urgent need of aid.