At least four people have died following overnight clashes ahead of Wednesday's rival protests in Venezuela by supporters and opponents of President Nicolas Maduro, police and a non-governmental organization said.

Thousands were beginning to assemble in Caracas ahead of the rival demonstrations on Wednesday, expected to be the first mass street rallies since 125 people died during protests between April and July, 2017.

A 16-year-old was among the dead overnight, having suffered "a firearm injury during a demonstration" in the capital Caracas, the Social Conflict Observatory said.

Police said the other three deaths occurred during looting in Bolivar City in the southeastern Bolivar State that borders Brazil.

A statue of iconic socialist revolutionary leader Hugo Chavez, Maduro's predecessor, was torched by dozens of protesters in the town of San Felix, Bolivar State.