CARACAS, Venezuela — Venezuela's authoritarian government claimed Monday that it had dismantled a covert operation to blow up power plants and oil facilities to destabilize the socialist state, saying it had detained eight plotters including an American traveling with heavy arms, explosives, surveillance footage and cash.

In a nationally televised address, Venezuelan Attorney General Tarek William Saab said active members of the Venezuelan military had aided the American, identified by authorities as Matthew John Heath. Saab said that Heath had a background working “as a mercenary” for U.S. intelligence in Iraq and that items in his possession had linked him to the CIA. Saab did not provide evidence for the claims.

“We have managed to neutralize an operation that could have been one of the worst in recent times,” Saab said. “A U.S. citizen and presumed military soldier was found to be carrying out espionage activities to destabilize Venezuelan territory. He had the help of Venezuelan citizens, both military and civilian.”

If true, the alleged plot would be the latest in a series of foiled operations against the government of President Nicolás Maduro. In May, two former U.S. Green Berets — Airan Berry, 42, and Luke Denman, 34 — were detained on the Venezuelan coast in connection with a ragtag raid aimed at capturing or ousting the autocratic leader.

In vague comments Friday, Maduro announced the arrest of a “U.S. marine” and “American spy” who had been apprehended a day earlier. Maduro said the U.S. citizen had been captured in a plot to blow up Venezuela’s El Palito refinery in Carabobo state.

“This is the vengeance of the Gringo Empire against Venezuela to stop our country from producing gas,” Maduro said.

On Monday, Saab offered more detail of an operation he said was designed to strike at Venezuela’s already troubled oil refineries and power grids.

State television broadcast images of weapons allegedly seized in the plot, including a grenade launcher, an Uzi submachine gun and packets of C4 explosives. They were splayed on a table alongside bundles of U.S. cash, cellphones and identification documents, including a grainy image of what appeared to be a copy of a U.S. passport.

Saab claimed Heath was detained in a car loaded with weapons and cash on a highway in the Venezuelan state of Falcón. He said Heath had entered the country illegally from Colombia with the aid of his Venezuelan ­co-conspirators. Saab said that Heath worked as “a contracted mercenary” in Iraq attached to MVM Inc., an Ashburn, Va.-based private security outfit, between 2006 and 2016.

Saab also said authorities had found a coin in Heath’s possession that linked him to the CIA. It was unclear whether he was referring to commonly issued souvenirs known as “challenge coins.”

Saab said Heath had a satellite phone and photos of several Venezuelan military installations and Venezuela’s largest oil refinery, located in Falcón state on the Caribbean coast.

Saab’s claims could not be verified independently. Unlike in the May arrest of the two former U.S. Green Berets, the Venezuelans produced no images or videos of Heath in custody or close-ups of his identification. Public records indicate a Matthew John Heath, 38, lived at Camp Lejeune in North Carolina in the early 2000s. There was no response at a number believed to belong to him.

The CIA declined to comment. Neither MVM nor the State Department responded to requests for comment.

The Trump administration considers Maduro illegitimate. The United States cut diplomatic ties with Maduro’s government last year and now backs opposition leader Juan Guaidó as the country’s rightful leader.

Berry and Denman were sentenced last month to 20 years in prison for conspiracy, illicit weapons trafficking and acts of terrorism for their roles in “Operation Gideon,” a bungled operation in which several dozen defectors from the Venezuelan military and police attempted to reenter the country to capture Maduro.

In a news conference shortly after that failed mission, Maduro showed a video of Denman’s apparent confession. Under interrogation by a man who was not visible, Denman said he worked with Jordan Goudreau, a Canadian-born naturalized U.S. citizen and former Green Beret who ran Silvercorp, a Florida-based security firm that helped organize the mission. A later video confession by Berry appeared to corroborate Denman’s account.

Denman’s relatives have said Goudreau, now a person of interest in an FBI investigation, falsely convinced Denman and Berry that they were taking part in a covert mission approved by the United States and the Venezuelan opposition. Goudreau could not be reached for comment Monday.

Venezuelan opposition figures have admitted to penning a preliminary deal with Goudreau last year to capture Maduro, but say they backed out after concluding he would be unable to pull off a mission successfully. The U.S. government denied involvement.

Sabotage of Venezuela’s crumbling refineries and power grid could severely damage Maduro, and such attacks have been among the many options discussed by factions of the Venezuelan opposition for months. Venezuela, an OPEC nation that harbors the world’s largest proven oil reserves, has very limited means to refine its own gasoline, and has suffered months of severe fuel shortages. Lines at the pump in some parts of the country have stretched for days, even weeks. Massive blackouts have grown common.

Faiola reported from Miami. Harris reported from Washington. Julie Tate and Alex Horton in Washington contributed to this report.