Venezuelan opposition lawmaker Juan Requesens has been arrested after President Nicolás Maduro accused him of involvement in Saturday's alleged drone attack against him.
His arrest came as a powerful government official revealed plans to strip two lawmakers of their immunity.
The government has blamed key opposition politicians for what they say was a bid to kill Mr Maduro.
But some government critics denounced the alleged attack as a "farce".
Who is Juan Requesens?
Juan Requesens is a member of the opposition-controlled National Assembly for the Primero Justicia (Justice First) party. The 29-year-old from the border state of Táchira is one of the most outspoken critics of President Maduro and has taken part in many anti-government demonstrations.
On Monday he gave a fiery speech in the Assembly, saying that government critics would not give up.
"We are going to continue doing everything we can to achieve what all of Venezuela wants, which is to get Nicolás Maduro out of power," he said.
He also accused the government of trying to silence the opposition. "The only strategy the dictatorship has is quash everyone who is different, be it inside or outside their ranks," he said.
What happened to him?
The party of Mr Requesens says he and his sister Rafaela, an opposition student activist, were taken away from their apartment in the capital, Caracas, by members of the secret police, Sebin.
Primero Justicia tweeted a video which appears to show CCTV footage of the two siblings getting out of the lift in an attempt to apparently leave the building.
Moments later, they are apparently pushed back by armed masked men in uniform, one of whom turns the camera to the wall.
Rafaela Requesens was later released but Juan Requesens has not been heard of since he was taken away.
Their father Juan Guillermo described what had happened to the two as a "kidnapping". "They were taken by force without any kind of warrant," he said.
What is he accused of?
Following Mr Requesens's arrest, President Maduro took to the airwaves to accuse him and another Primer Justicia lawmaker, Julio Borges, of having plotted Saturday's alleged drone attack on him.
He said that in their statements those already detained in connection with the incident had implicated the two opposition politicians.
"All of the statements point at Julio Borges, who lives in a mansion in [the Colombian capital] Bogotá protected by the outgoing government of Colombia," the president said without offering evidence of the statements.
"We know he has the cowardice needed to carry out an attack of this kind. I know that perfectly well. He has demonstrated that in the street protests of the last 15 years. It is always him, always Julio Borges. And now he has had the finger pointed at him directly."
President Maduro then turned on Mr Requesens, saying: "Another opposition leader is mentioned. One of the craziest and psychopathic ones, someone called Requesens… who a year ago called for the US army to invade and occupy Venezuela. They have been mentioned by the perpetrators."
It is not clear whether official charges have so far been brought against Mr Requesens.
What has the reaction been?
Writing on Twitter from outside Venezuela, Julio Borges rejected the accusations made against him and Juan Requesens.
"Neither the country nor the world believe you when it comes to this farce of an attack, we all know that it was staged to persecute and repress those of us who oppose your dictatorship," he wrote [in Spanish].
Was the attack staged?
Some in the opposition, like Mr Borges, think it was staged by the government to justify a further crackdown on the opposition.
They say the fact that the president of the powerful National Constituent Assembly, Diosdado Cabello, has called for a session later on Wednesday to strip the two lawmakers of their parliamentary immunity proves their point.
National Constituent Assembly
- Convened by President Maduro in 2016 ostensibly to rewrite Venezuela's constitution
- Entirely made up of government supporters
- Most decisions are approved unanimously by a mere show of hands
- Government critics say it was created to bypass the National Assembly
They say that the government itself launched two drones, one of which exploded near the podium where President Maduro was giving a speech on Saturday, to back its theory that the opposition are coup-plotters conspiring to bring the leader down with the help of Colombia and the US.
What evidence is there?
TV footage of the event shows President Maduro's wife looking up startled. Then an explosion is heard and the president's bodyguard is seen rushing to shield him.
A second, more muffled explosion can be heard and Mr Maduro leaves the stage.
The footage does not show any drones or explosions, only the startled expressions of those on the stage. This led many to speculate that there were no drones.
However, two videos have since emerged apparently showing two drones. One, published by Caracas News 24, shows a drone exploding:
An analysis carried out by website Bellingcat, which uses open-source information to investigate the incident, suggests that the video was taken on Bolívar Avenue, where President Maduro was speaking.
The second video reportedly taken by a cameraman for Telemundo and tweeted by journalist Adriana Núñez Rabascall appears to show a drone crashing against the wall of a building.
The building seems to be the same one where firefighters reported a fire shortly after President Maduro had left the stage.
However, three firefighters told the Associated Press news agency on Saturday that it had been caused by an exploding gas tank, casting doubt on the government's version of events.
Bellingcat concludes that there were two drones which "likely carried some form of explosive device" and which "attempted to attack a parade at which President Maduro was speaking".
Why would the attack be staged?
Those who believe it was staged say it allows the government to further tighten the screws on the opposition. However, government critic Blas Jesús Imbroda has dismissed that theory.
Mr Imbroda, who is the adviser to Venezuela's sacked former chief prosecutor, Luisa Ortega, argues that the "repression in Venezuela is constant and continuing and Maduro doesn't need to do anything to increase it".
Venezuela analyst David Smilde of the Washington Office on Latin America told the BBC he was sure it was not an event staged by the government because it looked "terrible".
"Maduro being interrupted in mid-set and one of his military officials fainting behind him and then the National Guard breaking rank and scattering, running for cover, I think the optics were absolutely terrible for him."
"This made him look highly vulnerable and it could spark the imagination of more people" Mr Smilde said.