Leopoldo Lopez, leader of the opposition Popular Will Party who turned himself into authorities Tuesday, was expected to face charges of murder, arson and terrorism Wednesday in connection with the simmering tension in the country, the worst in Maduro's 11 months in power, CNN reported.
Three anti-government protesters and one government supporter have been killed in clashes across the country. The government blames Lopez for inciting the crowds.
Lopez, who has organized protests calling for better security, an end to food shortages and enhanced freedom of speech for citizens, marched with a crowd of thousands in Caracas Tuesday before turning himself in to authorities, CNN said.
Hours later, Maduro told supporters the head of Venezuela's National Assembly helped negotiate the surrender of Lopez, and that Lopez was on his way to a prison outside Caracas. Maduro claimed opposition leaders were right-wing fascists with U.S. backing who have attempted to assassinate him and overthrow his democratically elected government.
Human rights organizations quickly condemned the perceived turning of protests into persecution of political opponents.
The charges against Lopez "smack of a politically motivated attempt to silence dissent," Amnesty International said in a statement.
Human Rights Watch warned Venezuela's leadership must avoid "scapegoating" political opponents.