The incident took place Saturday at a mine in the town of Guasipati, in Bolivar state, when "an exchange of shots with several still-unidentified suspects left 18 dead," including a woman, according to an unofficial military report seen by AFP.

Illegal gold mining is common in the area.

Five military rifles, seven pistols, three revolvers, a shotgun and two grenades were seized, according to the military report. The authorities have yet to issue any public statement.

Opposition lawmaker Americo De Grazia, a Bolivar state representative, denounced the operation, saying, "Did 18 citizens die and not a single soldier was injured? ... They 'clear' these gold areas with fire and blood."

And an NGO, the Venezuelan Program of Education Action in Human Rights, tweeted that the operation was "worrisome -- a new massacre?"

The region, which borders Brazil, forms part of the Orinoco Mining Arc, a vast area that the government exploits with multinational companies to make up for the falling oil revenues that have aggravated a serious economic and political crisis in Venezuela.

On September 14, 11 people died in an armed clash with soldiers in the town of Tumeremo, also in Bolivar state. Three weeks earlier, eight people were killed in El Callao, which is near both Tumeremo and Guasipati.

In March 2016, Tumeremo was the scene of a confrontation that left 17 miners dead, their bodies found later in a mass grave. A few months later 11 people were killed in the same town, where criminal groups often clash over control of gold deposits.