Guaido said on Twitter: 'The regime has kidnapped the first vice president.'
Caracas: Venezuelan intelligence agents detained opposition leader Juan Guaido's congressional deputy on Wednesday, using a tow truck to drag his vehicle away with him inside, prompting the US government to warn of "consequences" if he was not released.
The SEBIN intelligence agency seized Edgar Zambrano, vice president of the opposition-controlled National Assembly, which Guaido heads, in the first arrest of a lawmaker since Guaido tried to spark a military uprising last week to bring down President Nicolas Maduro's government.
Venezuela's pro-Maduro Constituent Assembly agreed on Tuesday to strip Zambrano and six other lawmakers of their parliamentary immunity to allow their future prosecution. The opposition does not recognize the assembly's decisions.
The Supreme Court had earlier accused those lawmakers of conspiracy, rebellion and treason, and accused another three opposition legislators of the same crimes on Wednesday.
The opposition says Maduro has stacked the court with his own supporters, while the US government this week threatened to sanction all its members.
The US government's Venezuelan embassy, now based in Washington, said Zambrano's "arbitrary detention" was "illegal and inexcusable."
"Maduro and his accomplices are those directly responsible for Zambrano's security. If he is not immediately freed, there will be consequences," the embassy said on Twitter.
An attempted uprising last week led by Guaido, recognized by the United States and other Western countries as the rightful head of state, failed to dislodge Maduro, as have a series of US sanctions against his government. Maduro decried the events as an attempted coup.
"One of the principal conspirators of the coup has just been arrested," Diosdado Cabello, head of the Constituent Assembly, said in comments broadcast on state television.
"They will have to pay before the courts for the failed coup that they attempted," he said.
Zambrano said on Twitter at about 6.40 pm local time (2240 GMT) SEBIN agents had surrounded his vehicle outside the headquarters of his Democratic Action party in Caracas' La Florida district.
"We were surprised by the SEBIN, and after refusing to let us leave our vehicle, they used a tow truck to forcibly transfer us directly to the (SEBIN headquarters) Helicoide," he said. It was not yet clear if Zambrano was already at the Helicoide.
Guaido said on Twitter: "The regime has kidnapped the first vice president."
Guaido invoked the constitution in January to assume an interim presidency, denouncing Maduro as illegitimate after he secured re-election last year in a vote widely viewed as fraudulent. Maduro has overseen the collapse of Venezuela's economy, which has shrunk by half over the past five years, forcing more than 3 million Venezuelans to emigrate.
The Constituent Assembly removed Guaido's parliamentary immunity in early April. Authorities have not tried to arrest him since then, but Maduro has said he will "face justice."
US President Donald Trump's administration has threatened Maduro's government with a harsh response should it ever detain Guaido.
Earlier on Wednesday, the Supreme Court's head, Maikel Moreno, rebuffed the US government's threats to sanction his court's members if they did not reject Maduro's government and Guaido.
The US Treasury Department imposed sanctions on Moreno and the seven principal members of the court's constitutional chamber in 2017 for rulings that "usurped the authority" of the National Assembly.
US Vice President Mike Pence said on Tuesday the Trump administration would soon sanction the 25 remaining members of the court. Pence said the United States was lifting economic sanctions on a former Venezuelan general who turned against Maduro in order to encourage other Maduro allies to follow suit.
The head of the Organization of American States, Luis Almagro, said: "We demand the SEBIN stop the intimidation, respect the lawmakers' parliamentary immunities, and immediately release Edgar Zambrano."