Two leading opposition figures are now behind bars in Venezuela, after overnight raids on their homes. The two men, both former mayors, were taken into custody by masked agents, just days after the controversial vote on a new assembly. 

Leopoldo Lopez and Antonio Ledezma were charged with "plans to flee" and "failing to comply" with the conditions of their house arrest, according to the Ministry of Communication and Information.

At the dead of night, 62-year-old mayor Ledezma was bundled out of his home by Venezuelan state security while he was still in his pajamas. At the same time, intelligence agents were taking Lopez from his home. 

Lopez, a 46-year-old economist who was educated at Harvard, is Venezuela's most popular opposition leader and was released from jail only last month. He had been expecting this to happen, so much so that he prepared a video in case.

"If you are watching this video right now, it is precisely because that is what happened. Because they came unjustly to make me an illegal prisoner. A prisoner of conscience, a prisoner because of my ideas, a prisoner for wanting a better Venezuela," said Lopez.

In violation of their terms, both men were actively campaigning against the elections held on Sunday for a National Constituent Assembly (ANC), urging supporters to boycott the initiative, the ministry said. The two are believed to be in a military prison outside Caracas.

The raids of the two leaders came just hours after the US government sanctioned President Nicolas Maduro. Washington accused him of being a "dictator after the vote to create an assembly that will overrule parliament here." Maduro, addressing the US leader as "Emperor Donald Trump", refuted that he will not heed "imperial orders."

"I will not obey imperial orders. I do not obey foreign governments. Not today nor tomorrow will I obey imperial orders," said Maduro.

President Maduro has taken issues with US sanctions targeting him personally. The US ordered a freeze on all of Maduro's assets subject to its jurisdiction, and banned its citizens from dealing with the Venezuelan leader. 

But some analysts say the sanctions against Maduro are only a symbolic measure designed to show Washington's disapproval of the Venezuelan leader, who defied a White House order to cancel Sunday's poll on the new constituent assembly. 

National crisis is still looming over the country, with US sanctions coming from outside and political opposition from within. Venezuela's Vice President Tareck El Ais-sami says the newly elected constituent assembly will convene within hours. But neither President Maduro nor he gave any specific time as yet. The assembly is said to be tasked with shaking up Venezuela's government and granting Maduro more power.