Venezuelan president Nicolas Maduro says police are hunting Leopoldo Lopez, the hardline opposition leader behind violent anti-government demonstrations that have ended with three deaths.
The socialist president's announcement on Saturday followed pro-government and student-led opposition demonstrations held in different parts of the capital, Caracas.
Lopez "ordered all these violent kids, which he trained, to destroy the prosecutor's office and half of Caracas and then goes into hiding", Maduro told thousands of supporters at a rally to denounce what he called a United States-backed, "fascist" plot to oust him from power. "Turn yourself in coward."
US officials have denied plotting to oust Maduro, and on Saturday Secretary of State John Kerry expressed concern over the rising tensions and violence surrounding the protests.
"These actions have a chilling effect on citizens' rights to express their grievances peacefully," Kerry said.
Maduro said security forces acting on an arrest order issued last week were now looking for Lopez, who has not been seen since a Wednesday night press conference in which he vowed that anti-government street protests would continue.
Maduro did not mention Lopez by name, referring to him only by a frequently used disparaging nickname, The Throne, to denote what he considers are the Harvard-trained politician's haughty political ambitions.
Still, his comments seemed to confirm a report by the El Universal newspaper which published a copy of an arrest order for Lopez on charges of vandalism of public property and terrorism.
Aides to Lopez denied he was evading arrest and said he remained in the country.