Two former Caracas mayors Antonio Ledezma and fellow opposition leader Leopoldo Lopez were jailed after being accused of destabilising President Maduro government.
Venezuelan intelligence agents have returned opposition leader Antonio Ledezma to his home, where he is serving house arrest, after taking him to prison early on Tuesday, Ledezma's family said on Friday.
The two former mayors of Caracas, Ledezma and fellow opposition leader Leopoldo Lopez were jailed after being accused of destabilising the government of President Nicolas Maduro.
A video posted on social media several days ago purported to show Ledezma under arrest and being dragged out of his home by police in uniforms emblazoned with the word Sebin, Venezuela's intelligence agency.
Ledezma posted a video on a social media website dated July 31 in which he called on Venezuelan people to continue fighting after a Constituent Assembly was elected on Sunday. The Assembly now supersedes an opposition-controlled congress that a pro-Maduro Supreme Court had already stripped of its powers.
Allegations over newly elected Constituent Assembly
Venezuela's electoral chief on Wednesday rejected allegations that Caracas had inflated the turnout figures for its Constituent Assembly election by at least one million votes, criticising the London firm's alleged evidence as "baseless."
The head of Venezuela's National Electoral Body Tibisay Lucena said the figures in question were managed exclusively by the Venezuelan government, and not the auditing firm.
Lucena was recently put on a list of sanctioned individuals by the US for undermining democracy in the OPEC nation.
She told the media that the tampering allegations were part of an "aggression" against Venezuela.
Electronic voting technology firm Smartmatic, which created the voting system used by Venezuela since 2004, said the turnout figures had been tampered with.
The accusations came hours after Reuters exclusively reported that only 3.7 million people had voted by 5:30pm in Sunday's (July 30) poll, according to internal elections data, compared to the 8.1 million people authorities said had voted that day.
The opposition boycotted Sunday's election of the Constituent Assembly, arguing that the rules were rigged to benefit the government, and nearly all the candidates were supporters of Maduro's administration.
Leaders of the opposition urged Venezuelans to fill the streets of the capital on Friday, hoping to provide a strong turnout to show that many people objected to the Assembly.
The body's 545 delegates were expected to be installed at the legislative palace in a room just metres from the chamber where the opposition-controlled National Assembly meets.
Maduro, who has said he will use the Assembly to punish his opponents, planned to attend the opening session.
"The only way they'll get us out of here is by killing us," declared Freddy Guevara, the National Assembly's first vice president.
"They will never have the seat that the people of Venezuela gave us."
Reactions over election results
The Vatican called on Friday for Venezuela's government to suspend its new legislative superbody and made a direct appeal to the security forces to avoid excessive force in dealing with opposition protests.
Current initiatives including the Constituent Assembly "create a climate of tension and conflict and take the future for granted", the Holy See Secretariat of State said in a statement, calling for the changes to be prevented or suspended.
The spiritual home of the world's 1.2 billion Catholics also urged Venezuela's security forces to avoid "excessive and disproportionate use of force."
More than 120 people have died in four months of opposition protests.
The Vatican statement called for a negotiated solution following the same guidelines the Vatican set out last year when it brokered talks between the government and the opposition which later broke down.
It also called on Venezuela to respect human rights and the country's current constitution.
Also, an increasing number of foreign governments have refused to recognise the Assembly and many within Venezuela fear it will create a one-party state.
"There has been a gradual erosion of democratic practise and this is a significant line that has been crossed," said Michael Shifter, president of the Washington-based think tank Inter-American Dialogue.
"To attach the term democracy to Venezuela with this new constituent Assembly is on very weak ground."
The US State Department called the Assembly illegitimate Thursday, saying the election was rigged to further entrench "the Maduro dictatorship."
"The United States will not recognise the National Constituent Assembly," spokeswoman Heath Nauert said.