Tension is mounting in the Venezuelan capital Caracas amid calls by the rival political camps for protests.
While supporters of President Nicolas Maduro attended an anti-imperialist rally in Caracas, those loyal to Opposition Leader Juan Guaido scuffled with police.
Mr Guaido called on his supporters to keep up the pressure on the Maduro government.
The governing Socialist Party called for a competing march to protest what it calls imperialism by the United States.
Washington has imposed crippling sanctions on Mr Maduro's government in a bid to cut off its sources of funding. Mr Maduro remains defiant.
In a tweet he said: "Today, when the US Empire tries to seize our natural resources, it intensifies its brutal aggression against our motherland. We stand firm in order to defend our land and shout: Yankee go home! We are anti-imperialist."
The rallies come amid a power crisis that led to the country's worst blackouts in decades.
Venezuela, which has the world’s largest oil reserves, was plunged into darkness on Thursday evening and many places were still without electricity on Saturday.
The ruling Socialist Party called the power cuts an act of US-sponsored sabotage but opposition critics said it was the result of two decades of mismanagement and corruption.