Venezuela's 'colectivos,' groups of armed civilian volunteers accused of committing violence on behalf of Nicolás Maduro's pariah regime, are poised to pounce on opposition protests.

Venezuelan opposition parties and NGOs decried the arrests of a prominent press freedom activist and a well-known opposition figure, among others, ahead of planned protests against Friday's inauguration of President Nicolas Maduro for his third term.

Venezuela's embattled opposition on Monday vowed to overcome "fear" and thwart President Nicolas Maduro's plans to be sworn in for another term, with defiant leaders renewing calls for mass protests and visiting the White House to rally international support.

Two U.S. citizens have been arrested in Venezuela, part of a group of seven who President Nicolas Maduro on Tuesday branded as "mercenaries," in the latest roundup ahead of the embattled leader's expected inauguration to a new term later this week.

Venezuelan opposition leader Edmundo González, who asserts victory in last year's presidential election against President Nicolás Maduro, reported on January 7 that his son-in-law was kidnapped in the capital.