President Nicolas Maduro angrily rejected US and other calls for dialogue as the protests, which have left four people dead, entered their third week.
Demonstrators -- students and opposition parties -- are angry over rampant street crime, runaway inflation, corruption and bleak job prospects in the country with the world's largest proven oil reserves.
Opposition leader Henrique Capriles, who has kept a low profile during the protests, today challenged Maduro to prove his claims that the demonstrations were part of a conspiracy to overthrow his government.
Prominent opposition leader Leopoldo Lopez, who has helped spearhead the protests, is meanwhile being held at a military jail, where his lawyers say he could remain for up to 45 days awaiting trial.
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Lopez, a 42-year-old Harvard-educated economist, has been charged with instigating violence, property damage and criminal association -- but not murder, as Maduro had threatened.
The student federations that have organized the protests across the country today called on "Venezuelan civil society to respond to the violence with white flowers."
The government meanwhile ordered a battalion of paratroopers to the border city of San Cristobal, where the student protests began on February 4, in response to what he said were reports of Colombians crossing "to carry out paramilitary missions."
In a televised news conference, he said a "de facto curfew" already was in place on the border, and he suggested that former Colombian president Alvaro Uribe was behind the border activity.