Hardline opposition leader Maria Corina Machado has been indicted by Venezuelan authorities on charges of taking part in a plot to kill the country’s president.
She could face up to 16 years in jail if found guilty.
The opposition heavyweight played a key role in leading nationwide protests against the government of President Nicolás Maduro earlier this year.
Fellow opposition heavyweight Leopoldo López remains behind bars on charges of inciting the protests and there is little hope for his imminent release.
Machado has not yet been detained.
Supporters of 47-year-old Machado see her detention as a crackdown on the opposition, as with López’s detention.
Yet the government see her as part of a larger plot, backed by the US government, to topple Venezuela’s revolution.
Maduro came to power a year and a half ago, after the death of Hugo Chavez.
The current president’s approval ratings are at an all-time low, hovering around 25%.
The country suffers annual inflation of more than 60 per cent, shortages of basic goods and one of the world’s highest murder rates.
Discontent within the poor, Maduro’s base of support, is falling.
Outside the state prosecutor's office, Machado, draped in a Venezuelan flag, vowed to fight on for “democracy and freedom.”